N-[2-(2-Amino-6,6-Disubstituted-4,4a,5,6-Tetrahydropyrano[3,4-d][1,3]Thiazin-8a(8H)-YL)-1,3-Thiazol-4-YL]Amides

ABSTRACT

The present invention is directed to compounds, tautomers and pharmaceutically acceptable salts of the compounds which are disclosed, wherein the compounds have the structure of Formula I, 
     
       
         
         
             
             
         
       
     
     and the variables R 1 , R 2  and R 3  are as defined in the specification. 
     Corresponding pharmaceutical compositions, methods of treatment, methods of synthesis, and intermediates are also disclosed.

FIELD OF THE INVENTION

The present invention relates to small molecule compounds andpharmaceutically acceptable salts thereof that are inhibitors of β-siteamyloid precursor protein (APP) Cleaving Enzyme 1 (BACE1) and inhibitorsof BACE2. This invention relates to inhibiting the production of A-betapeptides that can contribute to the formation of neurological depositsof amyloid protein. The present invention also relates to the treatmentof Alzheimer's disease (AD) and other neurodegenerative and/orneurological disorders, as well as the treatment of diabetes in mammals,including humans. More particularly, this invention relates tothioamidine compounds and pharmaceutically acceptable salts thereofuseful for the treatment of neurodegenerative and/or neurologicaldisorders, such as AD and Down's syndrome, related to A-beta peptideproduction.

BACKGROUND OF THE INVENTION

Dementia results from a wide variety of distinctive pathologicalprocesses. The most common pathological processes causing dementia areAlzheimer's disease (“AD”), cerebral amyloid angiopathy (“CM”) andprion-mediated diseases (see, e.g., Haan et al., Clin. Neurol.Neurosurg., 1990, 92(4):305-310; Glenner et al., J. Neurol. Sci., 1989,94:1-28). AD is a progressive, neurodegenerative disorder characterizedby memory impairment and cognitive dysfunction. AD affects nearly halfof all people past the age of 85, the most rapidly growing portion ofthe United States population. As such, the number of AD patients in theUnited States is expected to increase from about 4 million to about 14million by 2050.

The accumulation of amyloid-β (Aβ peptides) is believed to be one of theunderlying causes of Alzheimer's disease (AD), which is the most commoncause of cognitive decline in the elderly (Hardy & Allsop, TrendsPharmacol. Sci., 1991; 12(10):383-8; Selkoe, Behav. Brain Res., 2008;192(1):106-13). Aβ, the major protein constituent of amyloid plaques, isderived from sequential cleavage of the type I integral membraneprotein, amyloid precursor protein (APP) by two proteases, β- andγ-secretase. Proteolytic cleavage of APP by the β-site APP cleavingenzymes (BACE1 and BACE2) generates a soluble N-terminal ectodomain ofAPP (sAPPβ) and the C-terminal fragment C99. Subsequent cleavage of themembrane-bound C99 fragment by the γ-secretase liberates the various Aβpeptide species, of which Aβ40 and Aβ42 are the most predominant forms(Vassar et al., J. Neurosci., 2009; 29(41):12787-94; Marks & Berg,Neurochem. Res., 2010; 35:181-210). Therefore, limiting the generationof Aβ directly through inhibition of BACE1 is one of the most attractiveapproaches for the treatment of AD, as BACE1 inhibitors couldeffectively inhibit the formation of all predominant Aβ peptides.

In addition, it has been determined that BACE1 knock-out mice hadmarkedly enhanced clearance of axonal and myelin debris from degeneratedfibers, accelerated axonal regeneration, and earlier reinnervation ofneuromuscular junctions compared with littermate controls. These datasuggest BACE1 inhibition as a therapeutic approach to accelerateregeneration and recovery after peripheral nerve damage. (See Farah etal., J. Neurosci., 2011, 31(15): 5744-5754).

Insulin resistance and impaired glucose homoeostasis are importantindicators of Type 2 diabetes and are early risk factors of AD. Inparticular, there is a higher risk of sporadic AD in patients with Type2 diabetes and AD patients are more prone to Type 2 diabetes (Butler,Diabetes, 53:474-481, 2004.). Recently, it has also been proposed thatAD should be reconsidered as Type 3 diabetes (de la Monte, J. DiabetesSci. Technol., 2008; 2(6):1101-1113). Of special interest is the factthat AD and Type 2 diabetes share common pathogenic mechanisms andpossibly treatments (Park S. A., J. Clin. Neurol., 2011; 7:10-18; Raffa,Br. J. Clin. Pharmacol 2011, 71(3):365-376). Elevated plasma levels ofAβ, the product of BACE activities, were recently associated withhyperglycemia and obesity in humans (see Meakin et al., Biochem J.,2012, 441(1):285-96.; Martins, Journal of Alzheimer's Disease, 8 (2005)269-282). Moreover, increased Aβ production prompts the onset of glucoseintolerance and insulin resistance in mice (Cózar-Castellano, Am. J.Physiol. Endocrinol. Metab., 302:E1373-E1380, 2012; Delibegovic,Diabetologia (2011) 54:2143-2151). Finally, it is also suggested thatcirculating Aβ could participate in the development of atherosclerosisin both humans and mice (De Meyer, Atherosclerosis 216 (2011) 54-58;Catapano, Atherosclerosis 210 (2010) 78-87; Roher, Biochimica etBiophysica Acta 1812 (2011) 1508-1514).

Therefore, it is believed that BACE1 levels may play a critical role inglucose and lipid homoeostasis in conditions of chronic nutrient excess.Specifically, BACE1 inhibitors may be potentially useful for increasinginsulin sensitivity in skeletal muscle and liver as illustrated by thefact that reduction in BACE1 decreases body weight, protects againstdiet-induced obesity and enhances insulin sensitivity in mice (seeMeakin et al., Biochem. J. 2012, 441(1):285-96). Of equal interest isthe identification of LRP1 as a BACE1 substrate and the potential linkto atherosclerosis (Strickland, Physiol. Rev., 88: 887-918, 2008; Hyman,J. Biol. Chem., Vol. 280, No. 18, 17777-17785, 2005).

Likewise, inhibition of BACE2 is proposed as a treatment of Type 2diabetes with the potential to preserve and restore β-cell mass andstimulate insulin secretion in pre-diabetic and diabetic patients(WO2011/020806). BACE2 is a β-cell enriched protease that regulatespancreatic β cell function and mass and is a close homologue of BACE1.Pharmacological inhibition of BACE2 increases β-cell mass and function,leading to the stabilization of Tmem27. (See Esterhazy et al., CellMetabolism 2011, 14(3): 365-377). It is suggested that BACE2 inhibitorsare useful in the treatment and/or prevention of diseases associatedwith the inhibition of BACE2 (e.g., Type 2 diabetes, with the potentialto preserve and restore β-cell mass and stimulate insulin secretion inpre-diabetic and diabetic patients) (WO2011/020806).

Aminodihydrothiazine or thioamidine compounds are described inUS2009/0082560, WO 2009/091016 and WO 2010/038686 as useful inhibitorsof the β-secretase enzyme. Fused heterocyclic derivatives useful asinhibitors of the β-secretase enzyme are described in WO 2011071109 andcorresponding US 2012245155. Co-pending PCT application,PCT/IB2012/054198, filed by Pfizer Inc on Aug. 17, 2012, also describesaminodihydrothiazine compounds that are useful inhibitors of theβ-secretase enzyme. The present invention is directed to novelthioamidine compounds and their use in the treatment ofneurodegenerative diseases, including AD, as well as the treatment ofmetabolic diseases and conditions such as diabetes and obesity.

SUMMARY OF THE INVENTION

A first embodiment of a first aspect of the present invention is acompound of Formula I

wherein R¹ is selected from the group consisting of: C₁₋₆alkyloptionally substituted with one to three fluoro or with C₁₋₃alkoxy;C₅₋₉bicycloalkyl optionally substituted with one to three R⁴; and a 5-to 6-membered heteroaryl, having one to four heteroatoms independentlyselected from N, O or S, wherein at least one of the heteroatoms is Nand wherein said N is optionally substituted with R⁵; and wherein said5- to 6-membered heteroaryl is optionally substituted on carbon with oneto three R⁴; R² and R³ are each independently selected from C₁₋₆alkyl orC₃₋₇cycloalkyl; wherein the C₁₋₆alkyl is optionally substituted with oneto three fluoro or C₁₋₃alkoxy; or R² and R³ taken together with thecarbon to which they are attached form a C₃₋₆cycloalkyl ring or a 4- to6-membered heterocycloalkyl ring, each of which is optionally andindependently substituted with one to three fluoro, C₁₋₃alkyl orC₁₋₃alkoxy; R⁴ at each occurrence is independently selected from thegroup consisting of halogen, hydroxy, cyano, C₁₋₆alkyl, C₁₋₆alkoxy,C₃₋₆alkenyl, C₃₋₆alkenyloxy, C₃₋₆alkynyl, C₃₋₆alkynyloxy,C₁₋₆alkoxy-C₁₋₆alkyl, C₃₋₆cycloalkoxy, C₃₋₆cycloalkyl,C₃₋₆cycloalkyl-C₁₋₆alkyl, C₃₋₆cycloalkyl-C₁₋₆alkoxy, 4- to 6-memberedheterocycloalkyl and 4- to 6-membered heterocycloalkyl-C₁₋₆alkyl;wherein said C₁₋₆alkyl, C₁₋₆alkoxy, C₃₋₆alkenyl, C₃₋₆alkenyloxy,C₃₋₆alkynyl, C₃₋₆alkynyloxy, C₁₋₆alkoxy-C₁₋₆alkyl, C₃₋₆cycloalkoxy,C₃₋₆cycloalkyl, C₃₋₆cycloalkyl-C₁₋₆alkyl, C₃₋₆cycloalkyl-C₁₋₆alkoxy, 4-to 6-membered heterocycloalkyl and 4- to 6-memberedheterocycloalkyl-C₁₋₆alkyl are each optionally substituted with one tothree substituents independently selected from fluoro, chloro, hydroxy,cyano, methyl, fluoromethyl, difluoromethyl, trifluoromethyl, methoxy,fluoromethoxy, difluoromethoxy and trifluoromethoxy; and R⁵ is hydrogen,C₁₋₆alkyl, C₃₋₆alkenyl, C₃₋₆alkynyl, C₁₋₆alkoxy-C₁₋₆alkyl,C₃₋₆cycloalkyl, C₃₋₆cycloalkyl-C₁₋₆alkyl, 4- to 6-memberedheterocycloalkyl and 4- to 6-membered heterocycloalkyl-C₁₋₆alkyl;wherein said C₁₋₆alkyl, C₃₋₆alkenyl, C₃₋₆alkynyl, C₁₋₆alkoxy-C₁₋₆alkyl,C₃₋₆cycloalkyl, C₃₋₆cycloalkyl-C₁₋₆alkyl, 4- to 6-memberedheterocycloalkyl and 4- to 6-membered heterocycloalkyl-C₁₋₆alkyl areeach optionally substituted with one to three substituents independentlyselected from fluoro, chloro, hydroxy, cyano, methyl, fluoromethyl,difluoromethyl, trifluoromethyl, methoxy, fluoromethoxy, difluoromethoxyand trifluoromethoxy; or R⁴ and R⁵ taken together can be a C₃₋₅alkylene;or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.

Another embodiment of the present invention is a pharmaceuticalcomposition comprising compounds of Formula I, or a tautomer thereof ora pharmaceutically acceptable salt of said compound or tautomer, and apharmaceutically acceptable vehicle, diluent or carrier. Thepharmaceutical compositions described herein can be used for inhibitingproduction of amyloid-β protein and for inhibiting beta-site amyloidprecursor protein cleaving enzyme 1 (BACE1); for treating aneurodegenerative disease and, in particular, Alzheimer's disease; forinhibiting BACE1 and/or BACE2 activity for the therapeutic and/orprophylactic treatment of diseases and disorders characterized byelevated β-amyloid levels, including diabetes or Type 2 diabetes; forincreasing insulin sensitivity in skeletal muscle and liver in a mammal,including humans; and for treating and/or preventing obesity.

The present invention is also directed to methods of treatment employingthe compounds of Formula I such as:

(1) Methods of inhibiting BACE enzyme activity, by administering atherapeutically effective amount of a thioamidine compound of any of theembodiments of Formula I or a pharmaceutically acceptable salt thereof,and a pharmaceutically acceptable carrier, to a mammal or a patient inneed thereof.

(2) Methods for treating conditions or diseases of the central nervoussystem and neurological disorders in which the β-secretase enzyme isinvolved (such as migraine; epilepsy; Alzheimer's disease; Parkinson'sdisease; brain injury; stroke; cerebrovascular diseases (includingcerebral arteriosclerosis, cerebral amyloid angiopathy, hereditarycerebral hemorrhage, and brain hypoxia-ischemia); cognitive disorders(including amnesia, senile dementia, HIV-associated dementia,Alzheimer's disease, Huntington's disease, Lewy body dementia, vasculardementia, drug-related dementia, tardive dyskinesia, myoclonus,dystonia, delirium, Pick's disease, Creutzfeldt-Jacob disease, HIVdisease, Gilles de la Tourette's syndrome, epilepsy, muscular spasms anddisorders associated with muscular spasticity or weakness includingtremors, and mild cognitive impairment (“MCI”); mental deficiency(including spasticity, Down syndrome and fragile X syndrome); sleepdisorders (including hypersomnia, circadian rhythm sleep disorder,insomnia, parasomnia, and sleep deprivation) and psychiatric disorderssuch as anxiety (including acute stress disorder, generalized anxietydisorder, social anxiety disorder, panic disorder, post-traumatic stressdisorder, agoraphobia, and obsessive-compulsive disorder); factitiousdisorder (including acute hallucinatory mania); impulse controldisorders (including compulsive gambling and intermittent explosivedisorder); mood disorders (including bipolar I disorder, bipolar IIdisorder, mania, mixed affective state, major depression, chronicdepression, seasonal depression, psychotic depression, seasonaldepression, premenstrual syndrome (PMS), premenstrual dysphoric disorder(PDD), and postpartum depression); psychomotor disorder; psychoticdisorders (including schizophrenia, schizoaffective disorder,schizophreniform, and delusional disorder); drug dependence (includingnarcotic dependence, alcoholism, amphetamine dependence, cocaineaddiction, nicotine dependence, and drug withdrawal syndrome); eatingdisorders (including anorexia, bulimia, binge eating disorder,hyperphagia, obesity, compulsive eating disorders and pagophagia);sexual dysfunction disorders; urinary incontinence; neuronal damagedisorders (including ocular damage, retinopathy or macular degenerationof the eye, tinnitus, hearing impairment and loss, and brain edema),nerve injury treatment (including accelerating regeneration and recoveryafter peripheral nerve damage) and pediatric psychiatric disorders(including attention deficit disorder, attention deficit/hyperactivedisorder, conduct disorder, and autism) in a mammal, preferably a human,comprising administering to said mammal a therapeutically effectiveamount of a compound of Formula I or pharmaceutically acceptable saltthereof. The compounds of Formula I may also be useful for improvingmemory (both short-term and long-term) and learning ability. The textrevision of the fourth edition of the Diagnostic and Statistical Manualof Mental Disorders (DSM-IV-TR) (2000, American Psychiatric Association,Washington, D.C.) provides a diagnostic tool for identifying many of thedisorders described herein. The skilled artisan will recognize thatthere are alternative nomenclatures, nosologies, and classificationsystems for disorders described herein, including those as described inthe DMS-IV-TR, and that terminology and classification systems evolvewith medical scientific progress;

(3) Methods for treating a neurological disorder (such as migraine;epilepsy; Alzheimer's disease; Parkinson's disease; Niemann-Pick type C;brain injury; stroke; cerebrovascular disease; cognitive disorder; sleepdisorder) or a psychiatric disorder (such as anxiety; factitiousdisorder; impulse control disorder; mood disorder; psychomotor disorder;psychotic disorder; drug dependence; eating disorder; and pediatricpsychiatric disorder) in a mammal, preferably a human, comprisingadministering to said mammal a therapeutically effective amount of acompound of Formula I or pharmaceutically acceptable salt thereof;

(4) Methods for the treatment (e.g., delaying the progression or onset)of diabetes or diabetes-related disorders including Type 1 and Type 2diabetes, impaired glucose tolerance, insulin resistance, hyperglycemia,and diabetic complications such as atherosclerosis, coronary heartdisease, stroke, peripheral vascular disease, nephropathy, hypertension,neuropathy, and retinopathy;

(5) Methods for the treatment of obesity co-morbidities, such asmetabolic syndrome. Metabolic syndrome includes diseases, conditions ordisorders such as dyslipidemia, hypertension, insulin resistance,diabetes (e.g., Type 2 diabetes), coronary artery disease and heartfailure. For more detailed information on metabolic syndrome, see, e.g.,Zimmet, P. Z. et al., “The Metabolic Syndrome: Perhaps an EtiologicMystery but Far From a Myth—Where Does the International DiabetesFederation Stand?,” Medscape Diabetes & Endocrinology, 7(2), (2005); andAlberti, K. G. et al., The “Metabolic Syndrome—A New WorldwideDefinition,” Lancet, 366, 1059-62 (2005); and

(6) Methods for the treatment of nonalcoholic fatty liver disease(NAFLD) and hepatic insulin resistance;

The present invention is also directed to combination therapies whereinthe compounds of this invention may also be used in conjunction withother pharmaceutical agents for the treatment of the diseases,conditions and/or disorders described herein. Therefore, methods oftreatment that include administering compounds of the present inventionin combination with other pharmaceutical agents are also provided;

All patents, patent applications and references referred to herein arehereby incorporated by reference in their entirety.

Other features and advantages of this invention will be apparent fromthis specification and the appendant claims which describe theinvention. It is to be understood that both the foregoing and thefollowing detailed description are exemplary only and are notrestrictive of the invention as claimed.

DETAILED DESCRIPTION OF THE INVENTION

The present invention may be understood more readily by reference to thefollowing detailed description of exemplary embodiments of the inventionand the examples included therein. It is to be understood that thisinvention is not limited to specific methods of synthesis, which may ofcourse vary. It is also to be understood that the terminology usedherein is for the purpose of describing particular embodiments only andis not intended to be limiting.

In this specification and in the claims that follow, reference will bemade to a number of terms that shall be defined to have the followingmeanings:

As used herein, “eating disorders” refer to illnesses in which thepatient suffers disturbances in his/her eating behaviors and relatedthoughts and emotions. Representative examples of obesity-related eatingdisorders include overeating, bulimia, binge-eating disorder, compulsivedieting, nocturnal sleep-related eating disorder, pica, Prader-Willisyndrome, and night-eating syndrome.

“Patient” refers to warm-blooded animals such as, for example, guineapigs, mice, rats, gerbils, cats, rabbits, dogs, cattle, goats, sheep,horses, monkeys, chimpanzees, and humans.

The term “pharmaceutically acceptable” means the substance orcomposition must be compatible, chemically and/or toxicologically, withthe other ingredients comprising a formulation, and/or the mammal beingtreated therewith.

The term “therapeutically effective amount” means an amount of acompound of the present invention that (i) treats or prevents theparticular disease, condition, or disorder, (ii) attenuates,ameliorates, or eliminates one or more symptoms of the particulardisease, condition, or disorder, or (iii) prevents or delays the onsetof one or more symptoms of the particular disease, condition, ordisorder described herein.

The term “treating”, as used herein, unless otherwise indicated, meansreversing, alleviating, inhibiting the progress of, delaying theprogression of, delaying the onset of, or preventing the disorder orcondition to which such term applies, or one or more symptoms of suchdisorder or condition. The term “treatment”, as used herein, unlessotherwise indicated, refers to the act of treating as “treating” isdefined immediately above. The term “treating” also includes adjuvantand neo-adjuvant treatment of a subject. For the avoidance of doubt,reference herein to “treatment” includes reference to curative,palliative and prophylactic treatment, and to the administration of amedicament for use in such treatment.

The term “alkyl” refers to a linear or branched-chain saturatedhydrocarbyl substituent (i.e., a substituent obtained from a hydrocarbonby removal of a hydrogen); in one embodiment containing from one to sixcarbon atoms. Non-limiting examples of such substituents include methyl,ethyl, propyl (including n-propyl and isopropyl), butyl (includingn-butyl, isobutyl, sec-butyl and tert-butyl), pentyl, isoamyl, hexyl andthe like.

The term “alkoxy” refers to a linear or branched-chain saturatedhydrocarbyl substituent attached to an oxygen radical (i.e., asubstituent obtained from a hydrocarbon alcohol by removal of thehydrogen from the OH); in one embodiment containing from one to sixcarbon atoms. Non-limiting examples of such substituents includemethoxy, ethoxy, propoxy (including n-propoxy and isopropoxy), butoxy(including n-butoxy, isobutoxy, sec-butoxy and tert-butoxy), pentoxy,hexoxy and the like.

The term “alkenyl” refers to a linear or branched-chain hydrocarbylsubstituent (i.e., a substituent obtained from a hydrocarbon by removalof a hydrogen) which contains at least one carbon-carbon double bond; inone embodiment containing from three to six carbon atoms. Non-limitingexamples of such substituents include allyl, propenyl, butenyl,isobutenyl, butadienyl, pentenyl, pentadienyl, hexenyl, hexadienyl andthe like. The term “alkenyloxy” refers to an alkenyl group attached toan oxygen radical.

The term “alkynyl” refers to a linear or branched-chain hydrocarbylsubstituent (i.e., a substituent obtained from a hydrocarbon by removalof a hydrogen) which contains at least one carbon-carbon triple bond; inone embodiment containing from three to six carbon atoms. Non-limitingexamples of such substituents include propynyl, butynyl, isobutynyl,pentynyl, hexynyl and the like. The term “alkynyloxy” refers to analkynyl group attached to an oxygen radical.

The term “alkylene” refers to an alkanediyl group (i.e. a substituentobtained from a hydrocarbon by removal of two hydrogens); in oneembodiment containing from three to five carbons. Non-limiting examplesof such groups include propylene, butylene and pentylene.

In some instances, the number of carbon atoms in a hydrocarbylsubstituent (i.e., alkyl, cycloalkyl, etc.) is indicated by the prefix“C_(x)-C_(y)-” or “C_(x-y)”, wherein x is the minimum and y is themaximum number of carbon atoms in the substituent. Thus, for example,“C₁-C₆-alkyl” or “C₁₋₆ alkyl” refers to an alkyl substituent containingfrom 1 to 6 carbon atoms. Illustrating further, C₃-C₆cycloalkyl orC₃₋₆-cycloalkyl refers to saturated cycloalkyl group containing from 3to 6 carbon ring atoms.

The term “cycloalkyl” refers to a carbocyclic substituent obtained byremoving a hydrogen from a saturated carbocyclic molecule, for exampleone having three to six carbon atoms or having three to nine carbonatoms. The term “cycloalkyl” includes mono-, bi- and tricyclic saturatedcarbocycles, as well as bridged and fused ring carbocycles and alsospiro-fused carbocyclic ring systems. For example, the term“C₃₋₉cycloalkyl” means a radical of a three- to nine-membered ringsystem, which includes the groups cyclopropyl, cyclobutyl, cyclopentyl,cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, bicyclopentyl,bicyclohexyl, bicycloheptyl, bicyclooctyl, bicyclononyl, spiropentyl,spirohexyl, spiroheptyl, spirooctyl and spirononyl. The term“C₃₋₆cycloalkyl” means a radical of a three- to six-membered ringsystem, which includes the groups cyclopropyl, cyclobutyl, cyclopentyl,cyclohexyl, bicyclopentyl, bicyclohexyl, spiropentyl and spirohexyl. Theterm “C₃₋₆cycloalkoxy” refers to a three- to six-membered cycloalkylgroup attached to an oxygen radical. Examples include cyclopropoxy,cyclobutoxy, cyclopentoxy and cyclohexoxy.

In some instances, the number of atoms in a cyclic substituentcontaining one or more heteroatoms (i.e., heteroaryl orheterocycloalkyl) is indicated by the prefix “x- to y-membered”, whereinx is the minimum and y is the maximum number of atoms forming the cyclicmoiety of the substituent. Thus, for example, “4- to 6-memberedheterocycloalkyl” refers to a heterocycloalkyl containing from 4 to 6atoms, including one to three heteroatoms, in the cyclic moiety of theheterocycloalkyl. Likewise the phrase “5- to 6-membered heteroaryl”refers to a heteroaryl containing from 5 to 6 atoms, and “5- to10-membered heteroaryl” refers to a heteroaryl containing from 5 to 10atoms, each including one or more heteroatoms, in the cyclic moiety ofthe heteroaryl.

Furthermore the phases “5-membered heteroaryl” and “6-memberedheteroaryl” refer to a five-membered heteroaromatic ring system and asix-membered heteroaromatic ring system, respectively. The heteroatomspresent in these ring systems are selected from N, O and S.

The term “hydroxy” or “hydroxyl” refers to —OH. When used in combinationwith another term(s), the prefix “hydroxy” indicates that thesubstituent to which the prefix is attached is substituted with one ormore hydroxy substituents. Compounds bearing a carbon to which one ormore hydroxy substituents include, for example, alcohols, enols andphenol.

The term “halo” or “halogen” refers to fluorine (which may be depictedas —F), chlorine (which may be depicted as —Cl), bromine (which may bedepicted as —Br), or iodine (which may be depicted as —I).

The term “heterocycloalkyl” refers to a substituent obtained by removinga hydrogen from a saturated or partially saturated ring structurecontaining a total of the specified number of atoms, such as 4 to 6 ringatoms, wherein at least one of the ring atoms is a heteroatom (i.e.,oxygen, nitrogen, or sulfur), with the remaining ring atoms beingindependently selected from the group consisting of carbon, oxygen,nitrogen, and sulfur. In a group that has a heterocycloalkylsubstituent, the ring atom of the heterocycloalkyl substituent that isbound to the group may be a nitrogen heteroatom, or it may be a ringcarbon atom. Similarly, if the heterocycloalkyl substituent is in turnsubstituted with a group or substituent, the group or substituent may bebound to a nitrogen heteroatom, or it may be bound to a ring carbonatom.

The term “heteroaryl” refers to an aromatic ring structure containingthe specified number of ring atoms in which at least one of the ringatoms is a heteroatom (i.e., oxygen, nitrogen, or sulfur), with theremaining ring atoms being independently selected from the groupconsisting of carbon, oxygen, nitrogen, and sulfur. Examples ofheteroaryl substituents include 6-membered heteroaryl substituents suchas pyridyl, pyrazyl, pyrimidinyl, and pyridazinyl; and 5-memberedheteroaryl substituents such as triazolyl, imidazolyl, furanyl,thiophenyl, pyrazolyl, pyrrolyl, oxazolyl, isoxazolyl, thiazolyl,1,2,3-, 1,2,4-, 1,2,5-, or 1,3,4-oxadiazolyl and isothiazolyl. Theheteroaryl group can also be a bicyclic heteroaromatic group such asindolyl, benzofuranyl, benzothienyl, benzimidazolyl, benzothiazolyl,benzoxazolyl, benzoisoxazolyl, oxazolopyridinyl, imidazopyridinyl,imidazopyrimidinyl and the like. In a group that has a heteroarylsubstituent, the ring atom of the heteroaryl substituent that is boundto the group may be a ring nitrogen atom, or it may be a ring carbonatom. Similarly, if the heteroaryl substituent is in turn substitutedwith a group or substituent, the group or substituent may be bound to aring nitrogen atom, or it may be bound to a ring carbon atom. The term“heteroaryl” also includes pyridyl N-oxides and groups containing apyridine N-oxide ring. In addition, the heteroaryl group may contain anoxo group such as the one present in a pyridone group. Further examplesinclude furyl, thienyl, oxazolyl, thiazolyl, imidazolyl, pyrazolyl,triazolyl, tetrazolyl, isoxazolyl, isothiazolyl, oxadiazolyl,thiadiazolyl, pyridinyl, pyridazinyl, pyrimidinyl, pyrazinyl,pyridin-2(1H)-onyl, pyridazin-2(1H)-onyl, pyrimidin-2(1H)-onyl,pyrazin-2(1H)-onyl, imidazo[1,2-a]pyridinyl, andpyrazolo[1,5-a]pyridinyl. The heteroaryl can be further substituted asdefined herein.

Examples of single-ring heteroaryls and heterocycloalkyls includefuranyl, dihydrofuranyl, tetrahydrofuranyl, thiophenyl,dihydrothiophenyl, tetrahydrothiophenyl, pyrrolyl, isopyrrolyl,pyrrolinyl, pyrrolidinyl, imidazolyl, isoimidazolyl, imidazolinyl,imidazolidinyl, pyrazolyl, pyrazolinyl, pyrazolidinyl, triazolyl,tetrazolyl, dithiolyl, oxathiolyl, oxazolyl, isoxazolyl, thiazolyl,isothiazolyl, thiazolinyl, isothiazolinyl, thiazolidinyl,isothiazolidinyl, thiaoxadiazolyl, oxathiazolyl, oxadiazolyl (includingoxadiazolyl, 1,2,4-oxadiazolyl, 1,2,5-oxadiazolyl, or1,3,4-oxadiazolyl), pyranyl (including 1,2-pyranyl or 1,4-pyranyl),dihydropyranyl, pyridinyl, piperidinyl, diazinyl (including pyridazinyl,pyrimidinyl, piperazinyl, triazinyl (including s-triazinyl, as-triazinyland v-triazinyl), oxazinyl (including 2H-1,2-oxazinyl, 6H-1,3-oxazinyl,or 2H-1,4-oxazinyl), isoxazinyl (including o-isoxazinyl orp-isoxazinyl), oxazolidinyl, isoxazolidinyl, oxathiazinyl (including1,2,5-oxathiazinyl or 1,2,6-oxathiazinyl), oxadiazinyl (including2H-1,2,4-oxadiazinyl or 2H-1,2,5-oxadiazinyl), morpholinyl.

The term “heteroaryl” can also include, when specified, ring systemshaving two rings wherein such rings may be fused and wherein one ring isaromatic and the other ring is not fully part of the conjugated aromaticsystem (i.e., the heteroaromatic ring can be fused to a cycloalkyl orheterocycloalkyl ring). Non-limiting examples of such ring systemsinclude 5,6,7,8-tetrahydroisoquinolinyl, 5,6,7,8-tetrahydroquinolinyl,6,7-dihydro-5H-cyclopenta[b]pyridinyl,6,7-dihydro-5H-cyclopenta[c]pyridinyl,1,4,5,6-tetrahydrocyclopenta[c]pyrazolyl,2,4,5,6-tetrahydrocyclopenta[c]pyrazolyl,5,6-dihydro-4H-pyrrolo[1,2-b]pyrazolyl,6,7-dihydro-5H-pyrrolo[1,2-b][1,2,4]triazolyl,5,6,7,8-tetrahydro-[1,2,4]triazolo[1,5-a]pyridinyl,4,5,6,7-tetrahydropyrazolo[1,5-a]pyridinyl,4,5,6,7-tetrahydro-1H-indazolyl and 4,5,6,7-tetrahydro-2H-indazolyl. Itis to be understood that if a carbocyclic or heterocyclic moiety may bebonded or otherwise attached to a designated substrate through differingring atoms without denoting a specific point of attachment, then allpossible points are intended, whether through a carbon atom or, forexample, a trivalent nitrogen atom. For example, the term “pyridyl”means 2-, 3- or 4-pyridyl, the term “thienyl” means 2- or 3-thienyl, andso forth.

If substituents are described as “independently” having more than onevariable, each instance of a substituent is selected independent of theother(s) from the list of variables available. Each substituenttherefore may be identical to or different from the othersubstituent(s).

If substituents are described as being “independently selected” from agroup, each instance of a substituent is selected independent of theother(s). Each substituent therefore may be identical to or differentfrom the other substituent(s).

As used herein, the term “Formula I” may be hereinafter referred to as a“compound(s) of the invention,” “the present invention,” and “compoundof Formula I.” Such terms are also defined to include all forms of thecompound of Formula I, including hydrates, solvates, isomers,crystalline and non-crystalline forms, isomorphs, polymorphs, andmetabolites thereof. For example, the compounds of the invention, orpharmaceutically acceptable salts thereof, may exist in unsolvated andsolvated forms. When the solvent or water is tightly bound, the complexwill have a well-defined stoichiometry independent of humidity. When,however, the solvent or water is weakly bound, as in channel solvatesand hygroscopic compounds, the water/solvent content will be dependenton humidity and drying conditions. In such cases, non-stoichiometry willbe the norm.

The compounds of the invention may exist as clathrates or othercomplexes. Included within the scope of the invention are complexes suchas clathrates, drug-host inclusion complexes wherein the drug and hostare present in stoichiometric or non-stoichiometric amounts. Alsoincluded are complexes of the compounds of the invention containing twoor more organic and/or inorganic components, which may be instoichiometric or non-stoichiometric amounts. The resulting complexesmay be ionized, partially ionized, or non-ionized. For a review of suchcomplexes, see J. Pharm. Sci., 64 (8), 1269-1288 by Haleblian (August1975).

The compounds of the invention have asymmetric carbon atoms. Thecarbon-carbon bonds of the compounds of the invention may be depictedherein using a solid line (———) a solid wedge (

) or a dotted wedge (

). The use of a solid line to depict bonds to asymmetric carbon atoms ismeant to indicate that all possible stereoisomers (e.g., specificenantiomers, racemic mixtures, etc.) at that carbon atom are included.The use of either a solid or dotted wedge to depict bonds to asymmetriccarbon atoms is meant to indicate that only the stereoisomer shown ismeant to be included. It is possible that compounds of Formula I maycontain more than one asymmetric carbon atom. In those compounds, theuse of a solid line to depict bonds to asymmetric carbon atoms is meantto indicate that all possible stereoisomers are meant to be included.For example, unless stated otherwise, it is intended that the compoundsof Formula I can exist as enantiomers and diastereomers or as racematesand mixtures thereof. The use of a solid line to depict bonds to one ormore asymmetric carbon atoms in a compound of Formula I and the use of asolid or dotted wedge to depict bonds to other asymmetric carbon atomsin the same compound is meant to indicate that a mixture ofdiastereomers is present.

Stereoisomers of Formula I include cis and trans isomers, opticalisomers such as R and S enantiomers, diastereomers, geometric isomers,rotational isomers, conformational isomers, and tautomers of thecompounds of the invention, including compounds exhibiting more than onetype of isomerism; and mixtures thereof (such as racemates anddiastereomeric pairs). Also included are acid addition or base additionsalts wherein the counterion is optically active, for example, D-lactateor L-lysine, or racemic, for example, DL-tartrate or DL-arginine.

When any racemate crystallizes, crystals of two different types arepossible. The first type is the racemic compound (true racemate)referred to above wherein one homogeneous form of crystal is producedcontaining both enantiomers in equimolar amounts. The second type is theracemic mixture or conglomerate wherein two forms of crystal areproduced in equimolar amounts each comprising a single enantiomer.

The compounds of Formula I may exhibit the phenomenon of tautomerism;such tautomers are also regarded as compounds of the invention. Forexample, the compounds of Formula I may exist in several tautomericforms, including the 2-aminodihydrothiazine form, I, and the2-imino-tetrahydrothiazine form, I′. All such tautomeric forms, andmixtures thereof, are included within the scope of compounds of FormulaI.

Tautomers exist as mixtures of a tautomeric set in solution. In solidform, usually one tautomer predominates. Even though one tautomer may bedescribed, the present invention includes all tautomers of the compoundsof Formula I and salts thereof. Examples of tautomers are described bythe compounds of Formula I and I′ and, collectively and generically, arereferred to as compounds of Formula I.

The compounds of this invention may be used in the form of salts derivedfrom inorganic or organic acids. Depending on the particular compound, asalt of the compound may be advantageous due to one or more of thesalt's physical properties, such as enhanced pharmaceutical stability indiffering temperatures and humidities, or a desirable solubility inwater or oil. In some instances, a salt of a compound also may be usedas an aid in the isolation, purification, and/or resolution of thecompound.

Where a salt is intended to be administered to a patient (as opposed to,for example, being used in an in vitro context), the salt preferably ispharmaceutically acceptable. The term “pharmaceutically acceptable salt”refers to a salt prepared by combining a compound of Formula I with anacid whose anion, or a base whose cation, is generally consideredsuitable for human consumption. Pharmaceutically acceptable salts areparticularly useful as products of the methods of the present inventionbecause of their greater aqueous solubility relative to the parentcompound. For use in medicine, the salts of the compounds of thisinvention are non-toxic “pharmaceutically acceptable salts.” Saltsencompassed within the term “pharmaceutically acceptable salts” refer tonon-toxic salts of the compounds of this invention which are generallyprepared by reacting the free base with a suitable organic or inorganicacid.

Suitable pharmaceutically acceptable acid addition salts of thecompounds of the present invention, when possible, include those derivedfrom inorganic acids, such as hydrochloric, hydrobromic, hydrofluoric,boric, fluoroboric, phosphoric, metaphosphoric, nitric, carbonic,sulfonic, and sulfuric acids, and organic acids such as acetic,benzenesulfonic, benzoic, citric, ethanesulfonic, fumaric, gluconic,glycolic, isothionic, lactic, lactobionic, maleic, malic,methanesulfonic, trifluoromethanesulfonic, succinic, toluenesulfonic,tartaric, and trifluoroacetic acids. Suitable organic acids generallyinclude, for example, aliphatic, cycloaliphatic, aromatic, araliphatic,heterocyclic, carboxylic, and sulfonic classes of organic acids.

Specific examples of suitable organic acids include acetate,trifluoroacetate, formate, propionate, succinate, glycolate, gluconate,digluconate, lactate, malate, tartaric acid, citrate, ascorbate,glucuronate, maleate, fumarate, pyruvate, aspartate, glutamate,benzoate, anthranilate, stearate, salicylate, p-hydroxybenzoate,phenylacetate, mandelate, embonate (pamoate), methanesulfonate,ethanesulfonate, benzenesulfonate, pantothenate, toluenesulfonate,2-hydroxyethanesulfonate, sufanilate, cyclohexylaminosulfonate, algenicacid, β-hydroxybutyric acid, galactarate, galacturonate, adipate,alginate, butyrate, camphorate, camphorsulfonate,cyclopentanepropionate, dodecylsulfate, glycoheptanoate,glycerophosphate, heptanoate, hexanoate, nicotinate,2-naphthalesulfonate, oxalate, palmoate, pectinate, 3-phenylpropionate,picrate, pivalate, thiocyanate, and undecanoate.

Furthermore, where the compounds of the invention carry an acidicmoiety, suitable pharmaceutically acceptable salts thereof may includethe lighter alkali metal salts, i.e., sodium or potassium salts;alkaline earth metal salts, e.g., calcium or magnesium salts; and saltsformed with suitable organic ligands, e.g., quaternary ammonium salts.In another embodiment, base salts are formed from bases which formnon-toxic salts, including aluminum, arginine, benzathine, choline,diethylamine, diolamine, glycine, lysine, meglumine, olamine,tromethamine and zinc salts.

Organic salts may be made from secondary, tertiary or quaternary aminesalts, such as tromethamine, diethylamine, N,N′-dibenzylethylenediamine,chloroprocaine, choline, diethanolamine, ethylenediamine, meglumine(N-methylglucamine), and procaine. Basic nitrogen-containing groups maybe quaternized with agents such as lower alkyl (C₁-C₆) halides (e.g.,methyl, ethyl, propyl, and butyl chlorides, bromides, and iodides),dialkyl sulfates (e.g., dimethyl, diethyl, dibutyl, and diamylsulfates), long chain halides (e.g., decyl, lauryl, myristyl, andstearyl chlorides, bromides, and iodides), arylalkyl halides (e.g.,benzyl and phenethyl bromides), and others.

In one embodiment, hemisalts of acids and bases may also be formed, forexample, hemisulfate and hemicalcium salts.

Also within the scope of the present invention are so-called “prodrugs”of the compound of the invention. Thus, certain derivatives of thecompound of the invention which may have little or no pharmacologicalactivity themselves can, when administered into or onto the body, beconverted into the compound of the invention having the desiredactivity, for example, by hydrolytic cleavage. Such derivatives arereferred to as “prodrugs.” Further information on the use of prodrugsmay be found in “Pro-drugs as Novel Delivery Systems, Vol. 14, ACSSymposium Series (T. Higuchi and V. Stella) and “Bioreversible Carriersin Drug Design,” Pergamon Press, 1987 (ed. E. B. Roche, AmericanPharmaceutical Association). Prodrugs in accordance with the inventioncan, for example, be produced by replacing appropriate functionalitiespresent in the compounds of any of Formula I with certain moieties knownto those skilled in the art as “pro-moieties” as described, for example,in “Design of Prodrugs” by H. Bundgaard (Elsevier, 1985).

The present invention also includes isotopically labeled compounds,which are identical to those recited in Formula I, but for the fact thatone or more atoms are replaced by an atom having an atomic mass or massnumber different from the atomic mass or mass number usually found innature. Examples of isotopes that can be incorporated into compounds ofthe present invention include isotopes of hydrogen, carbon, nitrogen,oxygen, sulfur, fluorine and chlorine, such as ²H, ³H, ¹³C, ¹¹C, ¹⁴C,¹⁵N, ¹⁸O, ¹⁷O, ³²P, ³⁵S, ¹⁸F, and ³⁶Cl, respectively. Compounds of thepresent invention, prodrugs thereof, and pharmaceutically acceptablesalts of said compounds or of said prodrugs that contain theaforementioned isotopes and/or other isotopes of other atoms are withinthe scope of this invention. Certain isotopically labeled compounds ofthe present invention, for example those into which radioactive isotopessuch as ³H and ¹⁴C are incorporated, are useful in drug and/or substratetissue distribution assays. Tritiated, i.e., ³H, and carbon-14, i.e.,¹⁴C, isotopes are particularly preferred for their ease of preparationand detectability. Further, substitution with heavier isotopes such asdeuterium, i.e., ²H, can afford certain therapeutic advantages resultingfrom greater metabolic stability, for example increased in vivohalf-life or reduced dosage requirements and, hence, may be preferred insome circumstances. Isotopically labeled compounds of Formula I of thisinvention and prodrugs thereof can generally be prepared by carrying outthe procedures disclosed in the Schemes and/or in the Examples andPreparations below, by substituting a readily available isotopicallylabeled reagent for a non-isotopically labeled reagent.

A second embodiment of a first aspect of the present invention is acompound of Formula Ia

or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.

A third embodiment of a first aspect of the present invention is acompound of Formula Ib

or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.

A fourth embodiment of a first aspect of the present invention is thecompound of any one of the first through third embodiments of the firstaspect wherein R¹ is a 5-membered heteroaryl selected from the groupconsisting of pyrazolyl and oxazolyl; each optionally substituted oncarbon with one to two R⁴; and wherein said pyrazolyl is substituted onN with R⁵; R⁴ at each occurrence is independently selected from thegroup consisting of halogen, C₁₋₃alkyl, C₃₋₆cycloalkyl, andC₁₋₃alkoxy-C₁₋₃alkyl; wherein said C₁₋₃alkyl is optionally substitutedwith one to three fluoro; and R⁵ is C₁₋₃alkyl or C₃₋₆cycloalkyl, whereinsaid C₁₋₃alkyl is optionally substituted with one to three fluoro; or atautomer thereof or a pharmaceutically acceptable salt of said compoundor tautomer.

A fifth embodiment of a first aspect of the present invention is thecompound of the fourth embodiment of the first aspect wherein R¹ isselected from the group consisting of

R⁴ at each occurrence is independently selected from the groupconsisting of chloro, methyl, ethyl, isopropyl, isobutyl, fluoromethyl,difluoromethyl, trifluoromethyl, cyclopropyl, cyclobutyl andmethoxymethyl; and R⁵ is methyl, ethyl, isopropyl, difluoromethyl,cyclopropyl or cyclobutyl; or a tautomer thereof or a pharmaceuticallyacceptable salt of said compound or tautomer.

A sixth embodiment of the first aspect of the present invention is thecompound of the fifth embodiment of the first aspect wherein R¹ isselected from the group consisting of

R² and R³ are each methyl; R⁴ is fluoromethyl; and R⁵ is difluoromethyl;or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.

A seventh embodiment of a first aspect of the present invention is thecompound of any one of the first through third embodiments of the firstaspect wherein R¹ is a 6-membered heteroaryl selected from the groupconsisting of pyridinyl and pyrazinyl; each optionally substituted oncarbon with one to two R⁴; and R⁴ at each occurrence is independentlyselected from the group consisting of halogen, C₁₋₆alkyl, C₁₋₆alkoxy andC₃₋₆alkynyloxy; wherein said C₁₋₆alkyl and C₁₋₆alkoxy are optionallysubstituted with one to three fluoro; or a tautomer thereof or apharmaceutically acceptable salt of said compound or tautomer.

An eighth embodiment of a first aspect of the present invention is thecompound of the seventh embodiment of the first aspect wherein R¹ isselected from the group consisting of

andR⁴ at each occurrence is independently selected from the groupconsisting of fluoro, chloro, methyl, fluoromethyl, difluoromethyl,trifluoromethyl, methoxy, fluoromethoxy, difluoromethoxy,trifluoromethoxy, difluoropropoxy and butynyloxy; or a tautomer thereofor pharmaceutically acceptable salt of said compound or tautomer.

A ninth embodiment of a first aspect of the present invention is thecompound of the eighth embodiment of the first aspect wherein R¹ is

andR⁴ at each occurrence is independently selected from the groupconsisting of chloro, fluoro, methyl, but-2-ynyloxy, difluoromethoxy and1,1-difluoroethoxy; or a tautomer thereof or a pharmaceuticallyacceptable salt of said compound or tautomer.

A tenth embodiment of a first aspect of the present invention is thecompound of the ninth embodiment of the first aspect wherein R² and R³are each independently selected from the group consisting of methyl,fluoromethyl, methoxymethyl, ethyl and cyclopropyl; or a tautomerthereof or a pharmaceutically acceptable salt of said compound ortautomer.

An eleventh embodiment of a first aspect of the present invention is thecompound of the ninth embodiment of the first aspect wherein R² and R³taken together with the carbon to which they are attached form acyclopropyl, cyclobutyl or oxetanyl ring; or a tautomer thereof or apharmaceutically acceptable salt of said compound or tautomer.

A twelfth embodiment of a first aspect of the present invention is thecompound of the eighth embodiment of the first aspect wherein

R¹ is

andR⁴ is selected from the group consisting of difluoromethoxy,2,2-difluoropropoxy and but-2-ynyloxy; or a tautomer thereof or apharmaceutically acceptable salt of said compound or tautomer.

A thirteenth embodiment of a first aspect of the present invention isthe compound of the twelfth embodiment of the first aspect wherein R²and R³ are each methyl; or a tautomer thereof or a pharmaceuticallyacceptable salt of said compound or tautomer.

A fourteenth embodiment of a first aspect of the present invention isthe compound of the second embodiment of the first aspect wherein R¹ isa C₅₋₉bicycloalkyl; or a tautomer thereof or a pharmaceuticallyacceptable salt of said compound or tautomer.

A fifteenth embodiment of a first aspect of the present invention is thecompound of the fourteenth embodiment of the first aspect wherein R¹ isbicyclo[1.1.1]pentan-1-yl or bicyclo[1.1.1]pentan-2-yl; and R² and R³are each independently methyl or ethyl; or a tautomer thereof or apharmaceutically acceptable salt of said compound or tautomer.

A sixteenth embodiment of a first aspect of the present invention is thecompound of the second embodiment of the first aspect wherein R¹ isC₁₋₆alkyl optionally substituted with one to three fluoro or C₁₋₃alkoxy;or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.

A seventeenth embodiment of a first aspect of the present invention isthe compound of the sixteenth embodiment of the first aspect wherein R¹is 2-fluoropropan-2-yl or 2-methoxypropan-2-yl; and R² and R³ are eachmethyl; or a tautomer thereof or a pharmaceutically acceptable salt ofsaid compound or tautomer.

An eighteenth embodiment of the present invention is a compound of thefirst embodiment of the first aspect selected from the group consistingof:

-   N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyridine-2-carboxamide;-   N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyridine-2-carboxamide;-   N-{2-[cis-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;-   N-{2-[(4a′S,8a′S)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;-   N-{2-[(4a′R,8a′R)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;-   N-{2-[(4a′R,8a′R)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-chloropyridine-2-carboxamide;-   N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;-   N-{2-[(4aR,6S,8aR)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide-   N-{2-[(4aR,6R,8aR)-2-amino-6-(methoxymethyl)-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;-   N-{2-[(4aR,8aR)-2-amino-6,6-bis(fluoromethyl)-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;-   N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-1-(difluoromethyl)-1H-pyrazole-3-carboxamide;-   N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-1-(difluoromethyl)-1H-pyrazole-3-carboxamide;-   N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyrazine-2-carboxamide;-   N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyrazine-2-carboxamide;-   N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;-   N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(1,1-difluoroethoxy)pyridine-2-carboxamide;-   N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(1,1-difluoroethoxy)pyridine-2-carboxamide;-   N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(2,2-difluoropropoxy)pyrazine-2-carboxamide;-   N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(2,2-difluoropropoxy)pyrazine-2-carboxamide;-   N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyrazine-2-carboxamide;-   N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyrazine-2-carboxamide;-   N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-2-(fluoromethyl)-1,3-oxazole-4-carboxamide;-   N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-2-(fluoromethyl)-1,3-oxazole-4-carboxamide;-   N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)-3-methylpyridine-2-carboxamide;-   N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)-3-methylpyridine-2-carboxamide;-   N-{2-[(4aS,6S,8aS)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;-   N-{2-[(4aR,6R,8aR)-2-amino-6-ethyl-6-methyl-4, 4a,    5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;-   N-{2-[(4aS,6R,8aS)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;-   N-{2-[(4a′R,8a′R)-2′-amino-4a′,5′-dihydro-4′H-spiro[oxetane-3,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;-   N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-3-chloro-5-(difluoromethoxy)pyridine-2-carboxamide;-   N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-2-fluoro-2-methylpropanamide;-   N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-2-methoxy-2-methylpropanamide;-   N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}bicyclo[1.1.1]pentane-1-carboxamide;-   N-{2-[(4aR,6S,8aR)-2-amino-6-(fluoromethyl)-6-methyl-4, 4a,    5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;-   N-{2-[(4aR,6R,8aR)-2-amino-6-(fluoromethyl)-6-methyl-4, 4a,    5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;-   N-{2-[(4aR,6S,8aR)-2-amino-6-ethyl-6-methyl-4, 4a,    5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)-3-methylpyridine-2-carboxamide-   N-{2-[(4aR,6S,8aR)-2-amino-6-ethyl-6-methyl-4, 4a, 5,    6-tetrahydropyrano[3,    4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}bicyclo[1.1.1]pentane-2-carboxamide;-   N-{2-[(4a′S,8a′S)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclopropane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;-   N-{2-[(4a′R,8a′R)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclopropane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;-   N-{2-[(4aR,6S,8aR)-2-amino-6-(methoxymethyl)-6-methyl-4, 4a,    5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;    and-   N-{2-[(4a′R,8a′R)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-fluoropyridine-2-carboxamide;-   or a tautomer thereof or a pharmaceutically acceptable salt of said    compound or tautomer.

A nineteenth embodiment of a first aspect of the present invention isthe compoundN-{2-[(4a′R,8a′R)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.

A twentieth embodiment of a first aspect of the present invention is thecompoundN-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.

A twenty-first embodiment of a first aspect of the present invention isthe compoundN-{2-[(4aR,6S,8aR)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.

A twenty-second embodiment of a first aspect of the present invention isthe compoundN-{2-[(4aR,6R,8aR)-2-amino-6-(methoxymethyl)-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.

A twenty-third embodiment of a first aspect of the present invention isthe compoundN-{2-[(4aS,6S,8aS)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.

A twenty-fourth embodiment of a first aspect of the present invention isthe compoundN-{2-[(4aR,6R,8aR)-2-amino-6-(fluoromethyl)-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.

A first embodiment of a second aspect of the present invention is apharmaceutical composition comprising a therapeutically effective amountof a compound of any one of the first through twenty-fourth embodimentsof the first aspect, or a tautomer thereof or a pharmaceuticallyacceptable salt of said compound or tautomer, and a pharmaceuticallyacceptable vehicle, diluent or carrier.

A first embodiment of a third aspect of the present invention is amethod of inhibiting production of amyloid-β protein in a patient, themethod comprising administering a therapeutically effective amount of acompound of any one of the first through twenty-fourth embodiments ofthe first aspect, or a tautomer thereof or a pharmaceutically acceptablesalt of said compound or tautomer, to a patient in need of inhibition ofproduction of amyloid-β protein.

A second embodiment of a third aspect of the present invention is amethod of inhibiting beta-site amyloid precursor protein cleaving enzyme1 (BACE1) in a patient, the method comprising administering atherapeutically effective amount of a compound of any one of the firstthrough twenty-fourth embodiments of the first aspect, or a tautomerthereof or a pharmaceutically acceptable salt of said compound ortautomer, to a patient in need of inhibition of beta-site amyloidprecursor protein cleaving enzyme 1 (BACE1).

A third embodiment of a third aspect of the present invention is amethod for treating a neurodegenerative disease in a patient, the methodcomprising administering a therapeutically effective amount of acompound of any one of the first through twenty-fourth embodiments ofthe first aspect, or a tautomer thereof or a pharmaceutically acceptablesalt of said compound or tautomer, to a patient in need of treatmentthereof.

A fourth embodiment of a third aspect of the present invention is themethod of the third embodiment of the third aspect wherein theneurodegenerative disease is Alzheimer's disease.

A fifth embodiment of a third aspect of the present invention is amethod of treating or preventing diabetes in a patient, the methodcomprising administering a therapeutically effective amount of acompound of any one of the first through twenty-fourth embodiments ofthe first aspect, or a tautomer thereof or a pharmaceutically acceptablesalt of said compound or tautomer, to a patient in need of treatment orprevention thereof.

A sixth embodiment of a third aspect of the present invention is themethod of the fifth embodiment of the third aspect wherein the diabetesis Type 2 diabetes.

Further embodiments of the present invention include the use of acompound according to any one of first through twenty-fourth embodimentsof the first aspect of the present invention in the preparation of amedicament useful for treating the conditions, diseases and disorders asdescribed herein.

Typically, a compound of the invention is administered in an amounteffective to treat a condition as described herein. The compounds of theinvention are administered by any suitable route in the form of apharmaceutical composition adapted to such a route, and in a doseeffective for the treatment intended. Therapeutically effective doses ofthe compounds required to treat the progress of the medical conditionare readily ascertained by one of ordinary skill in the art usingpreclinical and clinical approaches familiar to the medicinal arts.

The compounds of the invention may be administered orally. Oraladministration may involve swallowing, so that the compound enters thegastrointestinal tract, or buccal or sublingual administration may beemployed, by which the compound enters the blood stream directly fromthe mouth.

In another embodiment, the compounds of the invention may also beadministered directly into the blood stream, into muscle, or into aninternal organ. Suitable means for parenteral administration includeintravenous, intraarterial, intraperitoneal, intrathecal,intraventricular, intraurethral, intrasternal, intracranial,intramuscular and subcutaneous. Suitable devices for parenteraladministration include needle (including microneedle) injectors,needle-free injectors and infusion techniques.

In another embodiment, the compounds of the invention may also beadministered topically to the skin or mucosa, that is, dermally ortransdermally. In another embodiment, the compounds of the invention canalso be administered intranasally or by inhalation. In anotherembodiment, the compounds of the invention may be administered rectallyor vaginally. In another embodiment, the compounds of the invention mayalso be administered directly to the eye or ear.

The dosage regimen for the compounds and/or compositions containing thecompounds is based on a variety of factors, including the type, age,weight, sex and medical condition of the patient; the severity of thecondition; the route of administration; and the activity of theparticular compound employed. Thus the dosage regimen may vary widely.Dosage levels of the order from about 0.01 mg to about 100 mg perkilogram of body weight per day are useful in the treatment of theabove-indicated conditions. In one embodiment, the total daily dose of acompound of the invention (administered in single or divided doses) istypically from about 0.01 to about 100 mg/kg. In another embodiment,total daily dose of the compound of the invention is from about 0.1 toabout 50 mg/kg, and in another embodiment, from about 0.5 to about 30mg/kg (i.e., mg compound of the invention per kg body weight). In oneembodiment, dosing is from 0.01 to 10 mg/kg/day. In another embodiment,dosing is from 0.1 to 1.0 mg/kg/day. Dosage unit compositions maycontain such amounts or submultiples thereof to make up the daily dose.In many instances, the administration of the compound will be repeated aplurality of times in a day (typically no greater than 4 times).Multiple doses per day typically may be used to increase the total dailydose, if desired.

For oral administration, the compositions may be provided in the form oftablets containing from about 0.01 mg to about 500 mg of the activeingredient, or in another embodiment, from about 1 mg to about 100 mg ofactive ingredient. Intravenously, doses may range from about 0.1 toabout 10 mg/kg/minute during a constant rate infusion.

Suitable subjects according to the present invention include mammaliansubjects. Mammals according to the present invention include, but arenot limited to, canine, feline, bovine, caprine, equine, ovine, porcine,rodents, lagomorphs, primates, and the like, and encompass mammals inutero. In one embodiment, humans are suitable subjects. Human subjectsmay be of either gender and at any stage of development.

In another embodiment, the invention comprises the use of one or morecompounds of the invention for the preparation of a medicament for thetreatment of the conditions recited herein.

For the treatment of the conditions referred to above, the compound ofthe invention can be administered as compound per se. Alternatively,pharmaceutically acceptable salts are suitable for medical applicationsbecause of their greater aqueous solubility relative to the parentcompound.

In another embodiment, the present invention comprises pharmaceuticalcompositions. Such pharmaceutical compositions comprise a compound ofthe invention presented with a pharmaceutically acceptable carrier. Thecarrier can be a solid, a liquid, or both, and may be formulated withthe compound as a unit-dose composition, for example, a tablet, whichcan contain from 0.05% to 95% by weight of the active compounds. Acompound of the invention may be coupled with suitable polymers astargetable drug carriers. Other pharmacologically active substances canalso be present.

The compounds of the present invention may be administered by anysuitable route, preferably in the form of a pharmaceutical compositionadapted to such a route, and in a dose effective for the treatmentintended. The active compounds and compositions, for example, may beadministered orally, rectally, parenterally, or topically.

Oral administration of a solid dose form may be, for example, presentedin discrete units, such as hard or soft capsules, pills, cachets,lozenges, or tablets, each containing a predetermined amount of at leastone compound of the present invention. In another embodiment, the oraladministration may be in a powder or granule form. In anotherembodiment, the oral dose form is sub-lingual, such as, for example, alozenge. In such solid dosage forms, the compounds of Formula I areordinarily combined with one or more adjuvants. Such capsules or tabletsmay contain a controlled-release formulation. In the case of capsules,tablets, and pills, the dosage forms also may comprise buffering agentsor may be prepared with enteric coatings.

In another embodiment, oral administration may be in a liquid dose form.Liquid dosage forms for oral administration include, for example,pharmaceutically acceptable emulsions, solutions, suspensions, syrups,and elixirs containing inert diluents commonly used in the art (e.g.,water). Such compositions also may comprise adjuvants, such as wetting,emulsifying, suspending, flavoring (e.g., sweetening), and/or perfumingagents.

In another embodiment, the present invention comprises a parenteral doseform. “Parenteral administration” includes, for example, subcutaneousinjections, intravenous injections, intraperitoneal injections,intramuscular injections, intrasternal injections, and infusion.Injectable preparations (e.g., sterile injectable aqueous or oleaginoussuspensions) may be formulated according to the known art using suitabledispersing, wetting agents, and/or suspending agents.

In another embodiment, the present invention comprises a topical doseform. “Topical administration” includes, for example, transdermaladministration, such as via transdermal patches or iontophoresisdevices, intraocular administration, or intranasal or inhalationadministration. Compositions for topical administration also include,for example, topical gels, sprays, ointments, and creams. A topicalformulation may include a compound which enhances absorption orpenetration of the active ingredient through the skin or other affectedareas. When the compounds of this invention are administered by atransdermal device, administration will be accomplished using a patcheither of the reservoir and porous membrane type or of a solid matrixvariety. Typical formulations for this purpose include gels, hydrogels,lotions, solutions, creams, ointments, dusting powders, dressings,foams, films, skin patches, wafers, implants, sponges, fibres, bandagesand microemulsions. Liposomes may also be used. Typical carriers includealcohol, water, mineral oil, liquid petrolatum, white petrolatum,glycerin, polyethylene glycol and propylene glycol. Penetrationenhancers may be incorporated; see, for example, J. Pharm. Sci., 88(10), 955-958, by Finnin and Morgan (October 1999).

Formulations suitable for topical administration to the eye include, forexample, eye drops wherein the compound of this invention is dissolvedor suspended in a suitable carrier. A typical formulation suitable forocular or aural administration may be in the form of drops of amicronized suspension or solution in isotonic, pH-adjusted, sterilesaline. Other formulations suitable for ocular and aural administrationinclude ointments, biodegradable (e.g., absorbable gel sponges,collagen) and non-biodegradable (e.g., silicone) implants, wafers,lenses and particulate or vesicular systems, such as niosomes orliposomes. A polymer such as cross-linked polyacrylic acid, polyvinylalcohol, hyaluronic acid, a cellulosic polymer, for example,hydroxypropylmethyl cellulose, hydroxyethyl cellulose, or methylcellulose, or a heteropolysaccharide polymer, for example, gelan gum,may be incorporated together with a preservative, such as benzalkoniumchloride. Such formulations may also be delivered by iontophoresis.

For intranasal administration or administration by inhalation, theactive compounds of the invention are conveniently delivered in the formof a solution or suspension from a pump spray container that is squeezedor pumped by the patient or as an aerosol spray presentation from apressurized container or a nebulizer, with the use of a suitablepropellant. Formulations suitable for intranasal administration aretypically administered in the form of a dry powder (either alone, as amixture, for example, in a dry blend with lactose, or as a mixedcomponent particle, for example, mixed with phospholipids, such asphosphatidylcholine) from a dry powder inhaler or as an aerosol sprayfrom a pressurized container, pump, spray, atomizer (preferably anatomizer using electrohydrodynamics to produce a fine mist), ornebulizer, with or without the use of a suitable propellant, such as1,1,1,2-tetrafluoroethane or 1,1,1,2,3,3,3-heptafluoropropane. Forintranasal use, the powder may comprise a bioadhesive agent, forexample, chitosan or cyclodextrin.

In another embodiment, the present invention comprises a rectal doseform. Such rectal dose form may be in the form of, for example, asuppository. Cocoa butter is a traditional suppository base, but variousalternatives may be used as appropriate.

Other carrier materials and modes of administration known in thepharmaceutical art may also be used. Pharmaceutical compositions of theinvention may be prepared by any of the well-known techniques ofpharmacy, such as effective formulation and administration procedures.The above considerations in regard to effective formulations andadministration procedures are well known in the art and are described instandard textbooks. Formulation of drugs is discussed in, for example,Hoover, John E., Remington's Pharmaceutical Sciences, Mack PublishingCo., Easton, Pa., 1975; Liberman et al., Eds., Pharmaceutical DosageForms, Marcel Decker, New York, N.Y., 1980; and Kibbe et al., Eds.,Handbook of Pharmaceutical Excipients (3^(rd) Ed.), AmericanPharmaceutical Association, Washington, 1999.

The compounds of the present invention can be used, alone or incombination with other therapeutic agents, in the treatment of variousconditions or disease states. The compound(s) of the present inventionand other therapeutic agent(s) may be may be administered simultaneously(either in the same dosage form or in separate dosage forms) orsequentially.

Two or more compounds may be administered simultaneously, concurrentlyor sequentially. Additionally, simultaneous administration may becarried out by mixing the compounds prior to administration or byadministering the compounds at the same point in time but at differentanatomic sites or using different routes of administration.

The phrases “concurrent administration,” “co-administration,”“simultaneous administration,” and “administered simultaneously” meanthat the compounds are administered in combination.

The present invention includes the use of a combination of a BACEinhibitor compound as provided in Formula I and one or more additionalpharmaceutically active agent(s). If a combination of active agents isadministered, then they may be administered sequentially orsimultaneously, in separate dosage forms or combined in a single dosageform. Accordingly, the present invention also includes pharmaceuticalcompositions comprising an amount of: (a) a first agent comprising acompound of Formula I or a pharmaceutically acceptable salt of thecompound; (b) a second pharmaceutically active agent; and (c) apharmaceutically acceptable carrier, vehicle or diluent.

The compounds of this invention may also be used in conjunction withother pharmaceutical agents for the treatment of the diseases,conditions and/or disorders described herein. Therefore, methods oftreatment that include administering compounds of the present inventionin combination with other pharmaceutical agents are also provided.Suitable pharmaceutical agents that may be used in combination with thecompounds of the present invention include, without limitation:

-   (i) anti-obesity agents (including appetite suppressants), include    gut-selective MTP inhibitors (e.g., dirlotapide, mitratapide and    implitapide, CCKa agonists (e.g., N-benzyl-2-[4-(l    H-indol-3-ylmethyl)-5-oxo-1-phenyl-4,5-dihydro-2,3,6,10b-tetraaza-benzo[e]azulen-6-yl]-N-isopropyl-acetamide    described in PCT Publication No. WO 2005/116034 or US Publication    No. 2005-0267100 A1), 5HT2c agonists (e.g., lorcaserin), MCR4    agonists (e.g., compounds described in U.S. Pat. No. 6,818,658),    lipase inhibitors (e.g., Cetilistat), PYY₃₋₃₆ (as used herein    “PYY₃₋₃₆” includes analogs, such as peglated PYY₃₋₃₆, e.g., those    described in US Publication 2006/0178501), opioid antagonists (e.g.,    naltrexone), oleoyl-estrone (CAS No. 180003-17-2), obinepitide    (TM30338), pram lintide (Symlin®), tesofensine (NS2330), leptin,    bromocriptine, orlistat, AOD-9604 (CAS No. 221231-10-3) and    sibutramine.-   (ii) anti-diabetic agents, such as an acetyl-CoA carboxylase (ACC)    inhibitor as described in WO2009144554, WO2003072197, WO2009144555    and WO2008065508, a diacylglycerol O-acyltransferase 1 (DGAT-1)    inhibitor, such as those described in WO09016462 or WO2010086820,    AZD7687 or LCQ908, a diacylglycerol O-acyltransferase 2 (DGAT-2)    inhibitor, a monoacylglycerol O-acyltransferase inhibitor, a    phosphodiesterase (PDE)-10 inhibitor, an AMPK activator, a    sulfonylurea (e.g., acetohexamide, chlorpropamide, diabinese,    glibenclamide, glipizide, glyburide, glimepiride, gliclazide,    glipentide, gliquidone, glisolamide, tolazamide, and tolbutamide), a    meglitinide, an α-amylase inhibitor (e.g., tendamistat, trestatin    and AL-3688), an α-glucoside hydrolase inhibitor (e.g., acarbose),    an α-glucosidase inhibitor (e.g., adiposine, camiglibose,    emiglitate, miglitol, voglibose, pradimicin-Q, and salbostatin), a    PPAR γ agonist (e.g., balaglitazone, ciglitazone, darglitazone,    englitazone, isaglitazone, pioglitazone and rosiglitazone), a PPAR    α/γ agonist (e.g., CLX-0940, GW-1536, GW-1929, GW-2433, KRP-297,    L-796449, LR-90, MK-0767 and SB-219994), a biguanide (e.g.,    metformin), a glucagon-like peptide 1 (GLP-1) modulator such as an    agonist (e.g., exendin-3 and exendin-4), liraglutide, albiglutide,    exenatide (Byetta®), albiglutide, taspoglutide, lixisenatide,    dulaglutide, semaglutide, NN-9924, TTP-054, a protein tyrosine    phosphatase-1B (PTP-1B) inhibitor (e.g., trodusquemine, hyrtiosal    extract, and compounds disclosed by Zhang, S. et al., Drug Discovery    Today, 12(9/10), 373-381 (2007)), a SIRT-1 inhibitor (e.g.,    resveratrol, GSK2245840 or GSK184072), a dipeptidyl peptidase IV    (DPP-IV) inhibitor (e.g., those in WO2005116014, sitagliptin,    vildagliptin, alogliptin, dutogliptin, linagliptin and saxagliptin),    an insulin secretagogue, a fatty acid oxidation inhibitor, an A2    antagonist, a c-jun amino-terminal kinase (JNK) inhibitor, a    glucokinase activator (GKa) such as those described in WO2010103437,    WO2010103438, WO2010013161, WO2007122482, TTP-399, TTP-355, TTP-547,    AZD1656, ARRY403, MK-0599, TAK-329, AZD5658 or GKM-001, insulin, an    insulin mimetic, a glycogen phosphorylase inhibitor (e.g.,    GSK1362885), a VPAC2 receptor agonist, an SGLT2 inhibitor, such as    those described in E. C. Chao et al., Nature Reviews Drug Discovery    9, 551-559 (July 2010) including dapagliflozin, canagliflozin,    BI-10733, tofogliflozin (CSG452), ASP-1941, THR1474, TS-071,    ISIS388626 and LX4211 as well as those in WO2010023594, a glucagon    receptor modulator such as those described in Demong, D. E. et al.,    Annual Reports in Medicinal Chemistry 2008, 43, 119-137, a GPR119    modulator, particularly an agonist, such as those described in    WO2010140092, WO2010128425, WO2010128414, WO2010106457, Jones, R. M.    et al., in Medicinal Chemistry 2009, 44, 149-170 (e.g., MBX-2982,    GSK1292263, APD597 and PSN821), an FGF21 derivative or an analog    such as those described in Kharitonenkov, A. et al., Current Opinion    in Investigational Drugs 2009, 10(4), 359-364, TGR5 (also termed    GPBAR1) receptor modulators, particularly agonists, such as those    described in Zhong, M., Current Topics in Medicinal Chemistry, 2010,    10(4), 386-396 and INT777, a GPR40 agonist, such as those described    in Medina, J. C., Annual Reports in Medicinal Chemistry, 2008, 43,    75-85, including but not limited to TAK-875, a GPR120 modulator,    particularly an agonist, a high-affinity nicotinic acid receptor    (HM74A) activator, and an SGLT1 inhibitor, such as GSK1614235. A    further representative listing of anti-diabetic agents that can be    combined with the compounds of the present invention can be found,    for example, at page 28, line 35 through page 30, line 19 of    WO2011005611. Preferred anti-diabetic agents are metformin and    DPP-IV inhibitors (e.g., sitagliptin, vildagliptin, alogliptin,    dutogliptin, linagliptin and saxagliptin). Other antidiabetic agents    could include inhibitors or modulators of carnitine palmitoyl    transferase enzymes, inhibitors of fructose 1,6-diphosphatase,    inhibitors of aldose reductase, mineralocorticoid receptor    inhibitors, inhibitors of TORC2, inhibitors of CCR2 and/or CCR5,    inhibitors of PKC isoforms (e.g., PKCa, PKCb, PKCg), inhibitors of    fatty acid synthetase, inhibitors of serine palmitoyl transferase,    modulators of GPR81, GPR39, GPR43, GPR41, GPR105, Kv1.3, retinol    binding protein 4, glucocorticoid receptor, somatostain receptors    (e.g., SSTR1, SSTR2, SSTR3 and SSTR5), inhibitors or modulators of    PDHK2 or PDHK4, inhibitors of MAP4K4, modulators of IL1 family    including IL1beta, and modulators of RXRalpha. In addition, suitable    anti-diabetic agents include mechanisms listed by Carpino, P. A.,    Goodwin, B. Expert Opin. Ther. Pat, 2010, 20(12), 1627-51;-   (iii) anti-hyperglycemic agents, for example, those described at    page 31, line 31 through page 32, line 18 of WO 2011005611;-   (iv) lipid lowering agents (for example, those described at page 30,    line 20 through page 31, line 30 of WO 2011005611), and    anti-hypertensive agents (for example, those described at page 31,    line 31 through page 32, line 18 of WO 2011005611);-   (v) acetylcholinesterase inhibitors, such as donepezil hydrochloride    (ARICEPT®, MEMAC), physostigmine salicylate (ANTILIRIUM®),    physostigmine sulfate (ESERINE), ganstigmine, rivastigmine    (EXELON®), ladostigil, NP-0361, galantamine hydrobromide (RAZADYNE®,    REMINYL®, NIVALIN®), tacrine (COGNEX®), tolserine, memoquin,    huperzine A (HUP-A; Neuro-Hitech), phenserine, bisnorcymserine (also    known as BNC), and INM-176;-   (vi) amyloid-β (or fragments thereof), such as Aβ₁₋₁₅ conjugated to    pan HLA DR-binding epitope (PADRE®), ACC-001 (Elan/Wyeth), and    Affitope;-   (vii) antibodies to amyloid-β (or fragments thereof), such as    ponezumab, solanezumab, bapineuzumab (also known as AAB-001),    AAB-002 (Wyeth/Elan), Gantenerumab, intravenous Ig (GAMMAGARD®),    LY2062430 (humanized m266; Lilly), and those disclosed in    International Patent Publication Nos WO04/032868, WO05/025616,    WO06/036291, WO06/069081, WO06/118959, in US Patent Publication Nos    US2003/0073655, US2004/0192898, US2005/0048049, US2005/0019328, in    European Patent Publication Nos EP0994728 and 1257584, and in U.S.    Pat. No. 5,750,349;-   (viii) amyloid-lowering or -inhibiting agents (including those that    reduce amyloid production, accumulation and fibrillization) such as    eprodisate (KIACTA®), celecoxib, lovastatin, anapsos, colostrinin,    pioglitazone, clioquinol (also known as PBT1), PBT2 (Prana    Biotechnology), flurbiprofen (ANSAID®, FROBEN®) and its R-enantiomer    tarenflurbil (FLURIZAN®), nitroflurbiprofen, fenoprofen (FENOPRON,    NALFON®), ibuprofen (ADVIL®, MOTRIN®, NUROFEN®), ibuprofen lysinate,    meclofenamic acid, meclofenamate sodium (MECLOMEN®), indomethacin    (INDOCIN®), diclofenac sodium (VOLTAREN®), diclofenac potassium,    sulindac (CLINORIL®), sulindac sulfide, diflunisal (DOLOBID®),    naproxen (NAPROSYN®), naproxen sodium (ANAPROX®, ALEVE®),    insulin-degrading enzyme (also known as insulysin), the gingko    biloba extract EGb-761 (ROKAN®, TEBONIN®), tramiprosate (CEREBRIL®,    ALZHEMED®), neprilysin (also known as neutral endopeptidase (NEP)),    scyllo-inositol (also known as scyllitol), atorvastatin (LIPITOR®),    simvastatin (ZOCOR®), ibutamoren mesylate, BACE inhibitors such as    LY450139 (Lilly), BMS-782450, and GSK-188909; gamma secretase    modulators and inhibitors such as ELND-007, BMS-708163    (Avagacestat), and DSP8658 (Dainippon); and RAGE (receptor for    advanced glycation end-products) inhibitors, such as TTP488    (Transtech) and TTP4000 (Transtech), and those disclosed in U.S.    Pat. No. 7,285,293, including PTI-777;-   (ix) alpha-adrenergic receptor agonists, and beta-adrenergic    receptor blocking agents (beta blockers); anticholinergics;    anticonvulsants; antipsychotics; calcium channel blockers; catechol    O-methyltransferase (COMT) inhibitors; central nervous system    stimulants; corticosteroids; dopamine receptor agonists and    antagonists; dopamine reuptake inhibitors; gamma-aminobutyric acid    (GABA) receptor agonists; immunosuppressants; interferons;    muscarinic receptor agonists; neuroprotective drugs; nicotinic    receptor agonists; norepinephrine (noradrenaline) reuptake    inhibitors; quinolines; and trophic factors;-   (x) histamine 3 (H3) antagonists, such as PF-3654746 and those    disclosed in US Patent Publication Nos US2005-0043354,    US2005-0267095, US2005-0256135, US2008-0096955, US2007-1079175, and    US2008-0176925; International Patent Publication Nos WO2006/136924,    WO2007/063385, WO2007/069053, WO2007/088450, WO2007/099423,    WO2007/105053, WO2007/138431, and WO2007/088462; and U.S. Pat. No.    7,115,600);-   (xi) N-methyl-D-aspartate (NMDA) receptor antagonists, such as    memantine (NAMENDA, AXURA, EBIXA), amantadine (SYMMETREL),    acamprosate (CAMPRAL), besonprodil, ketamine (KETALAR), delucemine,    dexanabinol, dexefaroxan, dextromethorphan, dextrorphan,    traxoprodil, CP-283097, himantane, idantadol, ipenoxazone, L-701252    (Merck), lancicemine, levorphanol (DROMORAN), methadone,    (DOLOPHINE), neramexane, perzinfotel, phencyclidine, tianeptine    (STABLON), dizocilpine (also known as MK-801), ibogaine, voacangine,    tiletamine, riluzole (RILUTEK), aptiganel (CERESTAT), gavestinel,    and remacimide;-   (xii) monoamine oxidase (MAO) inhibitors, such as selegiline    (EMSAM), selegiline hydrochloride (I-deprenyl, ELDEPRYL, ZELAPAR),    dimethylselegiline, brofaromine, phenelzine (NARDIL),    tranylcypromine (PARNATE), moclobemide (AURORIX, MANERIX),    befloxatone, safinamide, isocarboxazid (MARPLAN), nialamide    (NIAMID), rasagiline (AZILECT), iproniazide (MARSILID, IPROZID,    IPRONID), iproclozide, toloxatone (HUMORYL, PERENUM), bifemelane,    desoxypeganine, harmine (also known as telepathine or banasterine),    harmaline, linezolid (ZYVOX, ZYVOXID), and pargyline (EUDATIN,    SUPIRDYL);-   (xiii) phosphodiesterase (PDE) inhibitors, including (a) PDE1    inhibitors (b) PDE2 inhibitors (c) PDE3 inhibitors (d) PDE4    inhibitors (e) PDE5 inhibitors (f) PDE9 inhibitors (e.g.,    PF-04447943, BAY 73-6691 (Bayer AG) and those disclosed in US Patent    Publication Nos US2003/0195205, US2004/0220186, US2006/0111372,    US2006/0106035, and U.S. Ser. No. 12/118,062 (filed May 9, 2008)),    and (g) PDE10 inhibitors such as    2-({4-[1-methyl-4-(pyridin-4-yl)-1H-pyrazol-3-yl]phenoxy}methyl)quinoline    (PF-2545920);-   (xiv) serotonin (5-hydroxytryptamine) 1A (5-HT_(1A)) receptor    antagonists, such as spiperone, levo-pindolol, lecozotan;-   (xv) serotonin (5-hydroxytryptamine) 2C (5-HT_(2C)) receptor    agonists, such as vabicaserin, and zicronapine; serotonin    (5-hydroxytryptamine) 4 (5-HT₄) receptor agonists/antagonists, such    as PRX-03140 (Epix) and PF-04995274;-   (xvi) serotonin (5-hydroxytryptamine) 3C (5-HT_(3C)) receptor    antagonists, such as Ondansetron (Zofran);-   (xvii) serotonin (5-hydroxytryptamine) 6 (5-HT₆) receptor    antagonists, such as mianserin (TOLVON, BOLVIDON, NORVAL),    methiothepin (also known as metitepine), ritanserin, SB-271046,    SB-742457 (GlaxoSmithKline), Lu AE58054 (Lundbeck A/S), SAM-760, and    PRX-07034 (Epix);-   (xviii) serotonin (5-HT) reuptake inhibitors such as alaproclate,    citalopram (CELEXA, CIPRAMIL), escitalopram (LEXAPRO, CIPRALEX),    clomipramine (ANAFRANIL), duloxetine (CYMBALTA), femoxetine    (MALEXIL), fenfluramine (PONDIMIN), norfenfluramine, fluoxetine    (PROZAC), fluvoxamine (LUVOX), indalpine, milnacipran (IXEL),    paroxetine (PAXIL, SEROXAT), sertraline (ZOLOFT, LUSTRAL), trazodone    (DESYREL, MOLIPAXIN), venlafaxine (EFFEXOR), zimelidine (NORMUD,    ZELMID), bicifadine, desvenlafaxine (PRISTIQ), brasofensine,    vilazodone, cariprazine and tesofensine;-   (xix) Glycine transporter-1 inhibitors such as paliflutine,    ORG-25935, and ORG-26041; and mGluR modulators such as AFQ-059 and    amantidine;-   (xx) AMPA-type glutamate receptor modulators such as perampanel,    mibampator, selurampanel, GSK-729327, and    N-{(3S,4S)-4-[4-(5-cyanothiophen-2-yl)phenoxy]tetrahydrofuran-3-yl}propane-2-sulfonamide;-   (xxi) P450 inhibitors, such as ritonavir;-   (xxii) tau therapy targets, such as davunetide;    -   and the like.

The present invention further comprises kits that are suitable for usein performing the methods of treatment described above. In oneembodiment, the kit contains a first dosage form comprising one or moreof the compounds of the present invention and a container for thedosage, in quantities sufficient to carry out the methods of the presentinvention.

In another embodiment, the kit of the present invention comprises one ormore compounds of the invention.

General Synthetic Schemes

The compounds of Formula I may be prepared by the methods describedbelow, together with synthetic methods known in the art of organicchemistry, or modifications and transformations that are familiar tothose of ordinary skill in the art. The starting materials used hereinare commercially available or may be prepared by routine methods knownin the art [such as those methods disclosed in standard reference bookssuch as the Compendium of Organic Synthetic Methods, Vol. I-XII(published by Wiley-Interscience)]. Preferred methods include, but arenot limited to, those described below.

During any of the following synthetic sequences it may be necessaryand/or desirable to protect sensitive or reactive groups on any of themolecules concerned. This can be achieved by means of conventionalprotecting groups, such as those described in T. W. Greene, ProtectiveGroups in Organic Chemistry, John Wiley & Sons, 1981; T. W. Greene andP. G. M. Wuts, Protective Groups in Organic Chemistry, John Wiley &Sons, 1991; and T. W. Greene and P. G. M. Wuts, Protective Groups inOrganic Chemistry, John Wiley & Sons, 1999, which are herebyincorporated by reference.

Compounds of Formula I, or their pharmaceutically acceptable salts, canbe prepared according to the reaction Schemes discussed herein below.Unless otherwise indicated, the substituents in the Schemes are definedas above. Isolation and purification of the products is accomplished bystandard procedures, which are known to a chemist of ordinary skill.

It will be understood by one skilled in the art that the varioussymbols, superscripts and subscripts used in the schemes, methods andexamples are used for convenience of representation and/or to reflectthe order in which they are introduced in the schemes, and are notintended to necessarily correspond to the symbols, superscripts orsubscripts in the appended claims. Additionally, one skilled in the artwill recognize that in many cases, these compounds will be mixtures andenantiomers that may be separated at various stages of the syntheticschemes using conventional techniques, such as, but not limited to,crystallization, normal-phase chromatography, reversed phasechromatography and chiral chromatography, to afford single enantiomers.The schemes are representative of methods useful in synthesizing thecompounds of the present invention. They are not to constrain the scopeof the invention in any way.

Scheme 1 refers to the preparation of compounds of Formula I or FormulaIa. Referring to Scheme 1, the compound of Formula I or Ia can beprepared through removal of protecting group P¹ from a compound ofFormula II or II′, respectively. P¹ in this case refers to groups wellknown to those skilled in the art for amine protection. For example, P¹may be a benzoyl group (Bz), which can be cleaved via basic conditions,including but not limited to treatment with1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) in methanol. Alternatively, P¹may be one of many other protecting group suitable for amines, including9-fluorenylmethoxycarbonyl (Fmoc) or tert-butoxycarbonyl (BOC) and canbe cleaved under standard conditions known to one skilled in the art.

Scheme 2 refers to the preparation of compounds II′ wherein P¹ is Bz orBoc. Conversion of the bromothiazole of Formula III to the correspondingamine can be effected via a transition metal-catalyzed couplingreaction, such as palladium-mediated amination. An example includesusing a protected ammonia source, such as, but not limited to,1-(2,4-dimethoxyphenyl)methanamine and a suitable catalyst and ligandchoice, for example, tris(dibenzylideneacetone)dipalladium(0) anddi-tert-butyl[2′,4′,6′-tri(propan-2-yl)biphenyl-2-yl]phosphane.Alternatively, one can utilize a copper-mediated azide coupling method.One skilled in the art will recognize that the requisite protectedammonia source will need to be deprotected to afford compounds ofFormula II′. In the example utilizing1-(2,4-dimethoxyphenyl)methanamine, said deprotection can be effectedvia acidic hydrolysis, such as treatment with concentrated hydrochloricacid.

The compound of Formula II′ can be prepared from the compound of FormulaIV via a standard peptide coupling with a carboxylic acid (R¹CO₂H), anda suitable coupling reagent, for example, but not limited to,O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluroniumhexafluorophosphate (HATU). Compounds of Formula II′ can be convertedinto a compound of Formula Ia according to the methods of Scheme 1. Itis to be understood that the reactions depicted in the Schemes arerepresentative and can be used to prepare compounds of Formulae I, Iaand Ib.

Scheme 3 refers to an alternative preparation of compounds II′ whereinP¹ is Bz or Boc. Conversion of the bromothiazole of Formula III to acompound of Formula V can be effected via a transition metal-catalyzedcoupling reaction, such as a palladium-mediated amination. An exampleincludes using a protected ammonia source, such as, but not limited to,1-(2,4-dimethoxyphenyl)methanamine and a suitable catalyst and ligandchoice, for example, tris(dibenzylideneacetone)dipalladium(0) anddi-tert-butyl[2′,4′,6′-tri(propan-2-yl)biphenyl-2-yl]phosphane. Thecompound of Formula VI can be prepared from the compound of Formula Vvia a standard peptide coupling with a carboxylic acid, and a suitablecoupling reagent, for example but not limited to,O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluroniumhexafluorophosphate (HATU). The compound of Formula II′ can be preparedfrom the compound of Formula VI via a deprotection effected via acidichydrolysis, such as treatment with concentrated trifluoroacetic acid.Compounds of Formula II′ can be converted into a compound of Formula Iaaccording to the methods of Scheme 1.

Scheme 4 refers to a preparation of compounds III wherein P¹ is Bz orBoc. Oxazolines of Formula VII can be transformed to oxazolidines ofFormula VIII via the addition of an appropriately metalated2,4-dibromo-1,3-thiazole (generated, for example, through treatment withn-butyllithium) and boron trifluoride diethyl etherate. Aminoalcohols ofFormula IX can be prepared through the reduction of compound VIII with areducing agent, such as, but not limited to, molybdenum hexacarbonyl andsodium borohydride. Compounds of Formula III can then be prepared viatreatment with the appropriate isothiocyanate (such as benzoylisothiocyanate), and subsequent ring closure using1-chloro-N,N,2-trimethylprop-1-en-1-amine (Ghosez's reagent). Compoundsof Formula III can be converted into a compound of Formula Ia accordingto the methods of Scheme 3, 2, and 1.

Scheme 5 refers to the preparation of compounds of Formula VII. Thealkylation of compounds of Formula XI can be effected using2-bromo-1,1-diethoxyethane and sodium hydride in tetrahydrofuran.Deprotection of the diethyl acetal of compounds of Formula XII can beachieved using acidic conditions; subsequent oxime formation occurs viatreatment with hydroxylamine hydrochloride to afford compounds ofFormula XIII. Treatment with sodium hypochlorite and triethylamine canthen afford isoxazoline VII. A compound of Formula VII can besubsequently converted into a compound of Formula I according to themethods of Schemes 4, 3, 2 and 1.

Scheme 6 refers to an alternative preparation of compounds of FormulaVII. The alkylation of compounds of Formula XI can be effected using2-nitroethanol and camphorsulfonic acid in dichloromethane. Treatmentwith di-tert-butyl dicarbonate and 4-(dimethylamino)pyridine (DMAP) indichloromethane can afford isoxazolines of Formula VII. A compound ofFormula VII can be converted into a compound of Formula I according tothe methods of Schemes 4, 3, 2 and 1.

Scheme 7 refers to the preparation of compounds III from the diolcompound of Formula XV, wherein P¹ is Bz or Boc. Methods for convertingalcohols to compounds of Formula III wherein R² and R³ are as definedherein are known to one skilled in the art. For example, one of thehydroxyl groups in compound XV can be protected as thetert-butyldimethylsilyl ether and the other hydroxyl can then beconverted to the corresponding p-toluenesulfonate. The resultingcompound can then be cyclized via treatment with tetrabutylammoniumfluoride, to provide a compound of Formula III in which R² and R³ takentogether with the carbon to which they are attached form an oxetanering. Alternatively, both hydroxyl groups in the compound XV can beconverted to iodo and the resulting compound can undergo a benzoylperoxide-induced radical cyclization to provide a compound of FormulaIII in which R² and R³ together with the carbon to which they areattached form a cyclopropyl ring. Other reaction sequences employingdifferential protection and reaction of the hydroxyl groups in thecompound XV can provide compounds of Formula III wherein R² and R³ havebeen differentiated (e.g., one of R² and R³ is methyl and the other isfluoromethyl or methoxymethyl). Alternatively, both of the hydroxylgroups in compound XV can be treated with an appropriate fluorinatingreagent to provide a compound of Formula III in which both R² and R³ arefluoromethyl. It is to be understood by one skilled in the art thatthere are numerous synthetic methodologies available for converting thediol XV to many varied R² and R³ groups in the compound of Formula III.The resulting compounds of Formula III can be converted into a compoundof Formula I according to the methods described herein.

Scheme 8 refers to the preparation of compounds of Formula XV wherein P¹is Bz or Boc. Oxazoline XVI (see C. R. Butler et al., J. Med. Chem.2015, 58, 2678-2702) is transformed to the oxazolidine of Formula XVIIvia the addition of an appropriately metallated 2,4-dibromo-1,3-thiazole(generated, for example, through treatment with n-butyllithium) andboron trifluoride diethyl etherate. The aminoalcohol of Formula XVIII isprepared through the reduction of compound XVII with a reducing agent,such as, but not limited to, molybdenum hexacarbonyl and sodiumborohydride. Compounds of Formula XX are then prepared via the treatmentwith the appropriate isothiocyanate (such as benzoyl isothiocyanate),and subsequent ring closure and benzyl deprotection usingp-toluenesulfonic acid and methoxybenzene. Oxidation can be effectedusing 1,1,1-tris(acetyloxy)-1,1-dihydro-1,2-benziodoxol-3-(1H)-one(Dess-Martin periodinane) to provide the corresponding aldehyde ofFormula XXI. Subsequent treatment with formaldehyde and sodium hydroxidein 1,4-dioxane and water can then yield compounds of Formula XV. Acompound of Formula XV can be converted into a compound of Formula Iaccording to the methods of Schemes 7, 3, 2 and 1.

Experimental Procedures

The following illustrate the synthesis of various compounds of thepresent invention. Additional compounds within the scope of thisinvention may be prepared using the methods illustrated in theseExamples, either alone or in combination with techniques generally knownin the art.

Experiments were generally carried out under inert atmosphere (nitrogenor argon), particularly in cases where oxygen- or moisture-sensitivereagents or intermediates were employed. Commercial solvents andreagents were generally used without further purification. Anhydroussolvents were employed where appropriate, generally AcroSeal® productsfrom Acros Organics or DriSolv® products from EMD Chemicals. In othercases, commercial solvents were passed through columns packed with 4 Åmolecular sieves, until the following QC standards for water wereattained: a) <100 ppm for dichloromethane, toluene,N,N-dimethylformamide and tetrahydrofuran; b) <180 ppm for methanol,ethanol, 1,4-dioxane and diisopropylamine. For very sensitive reactions,solvents were further treated with metallic sodium, calcium hydride ormolecular sieves, and distilled just prior to use. Products weregenerally dried under vacuum before being carried on to furtherreactions or submitted for biological testing. Mass spectrometry data isreported from either liquid chromatography-mass spectrometry (LCMS),atmospheric pressure chemical ionization (APCI) or gaschromatography-mass spectrometry (GCMS) instrumentation. Chemical shiftsfor nuclear magnetic resonance (NMR) data are expressed in parts permillion (ppm, δ) referenced to residual peaks from the deuteratedsolvents employed. In some examples, chiral separations were carried outto separate enantiomers of certain compounds of the invention (in someexamples, the separated enantiomers are designated as ENT-1 and ENT-2,according to their order of elution). In some examples, the opticalrotation of an enantiomer was measured using a polarimeter. According toits observed rotation data (or its specific rotation data), anenantiomer with a clockwise rotation was designated as the(+)-enantiomer and an enantiomer with a counter-clockwise rotation wasdesignated as the (−)-enantiomer. Racemic compounds are indicated by thepresence of (+/−) adjacent to the structure; in these cases, indicatedstereochemistry represents the relative (rather than absolute)configuration of the compound's substituents.

Reactions proceeding through detectable intermediates were generallyfollowed by LCMS, and allowed to proceed to full conversion prior toaddition of subsequent reagents. For syntheses referencing procedures inother Examples or Methods, reaction conditions (reaction time andtemperature) may vary. In general, reactions were followed by thin-layerchromatography or mass spectrometry, and subjected to work-up whenappropriate. Purifications may vary between experiments: in general,solvents and the solvent ratios used for eluents/gradients were chosento provide appropriate R_(f)s or retention times. All starting materialsin these Preparations and Examples are either commercially available orcan be prepared by methods known in the art or as described herein.

The following are abbreviations which may appear in the experimentalprocedures described herein.

Abbreviations: br=broad; CDCl₃=deuteron-chloroform;CD₃OD=deuteron-methanol; d=doublet; dd=doublet of doublets; dddd=doubletof doublet of doublet of doublets; g=gram; h=hour; HPLC=high-performanceliquid chromatography; Hz=hertz; L=liter; LCMS=liquid chromatographymass spectroscopy; min=minutes; m=multiplet; M=molar; MHz=megahertz;mmol=millimole; μmol=micromole; mL=milliliter; μL=microliter; mol=mole;NOE=Nuclear Overhauser effect; s=singlet; tr=triplet; q=quartet.

Preparation P1N-[cis-8a-(4-Amino-1,3-thiazol-2-yl)-6,6-dimethyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P1)

Step 1. Synthesis of 4-(2,2-diethoxyethoxy)-4-methylpent-1-ene (C1)

2-Methylpent-4-en-2-ol (89 g, 0.89 mol) was added drop-wise to asuspension of sodium hydride (60% in mineral oil; 107 g, 2.67 mol) intetrahydrofuran (1.5 L). The reaction mixture was stirred for 45 minutesat room temperature, whereupon 2-bromo-1,1-diethoxyethane (90%, 292 g,1.33 mol) was slowly added. After the reaction mixture had been heatedat reflux for 36 hours, it was poured into ice water (2 L) and extractedwith ethyl acetate (3×1 L). The combined organic layers were washed withsaturated aqueous sodium chloride solution (2×1.5 L), dried over sodiumsulfate, filtered, and concentrated in vacuo. Purification viachromatography on alumina (Eluent: petroleum ether) afforded the productas a yellow oil. By ¹H NMR, this material contained a significantpercentage of 2-bromo-1,1-diethoxyethane; half of this material wastaken directly to the following step. ¹H NMR (400 MHz, CDCl₃),characteristic product peaks: δ 5.92-5.78 (m, 1H), 5.06 (s, 1H),5.05-5.01 (m, 1H), 4.68 (t, J=5.5 Hz, 1H), 3.43 (d, J=5.3 Hz, 2H), 2.24(br d, J=7.3 Hz, 2H).

Step 2. Synthesis of N-hydroxy-2-[(2-methylpent-4-en-2-yl)oxy]ethanimine(C2)

To a solution of C1 (from the previous step; 85.0 g, 445 mmol) inethanol (1.4 L) and water (700 mL) was added hydroxylamine hydrochloride(81.9 g, 1.18 mol) at room temperature. The reaction mixture was stirredat 50° C. for 15 hours, whereupon it was extracted with dichloromethane(2×100 mL). The combined organic layers were washed with saturatedaqueous sodium chloride solution (2×1 L), dried over sodium sulfate,filtered, and concentrated in vacuo. Silica gel chromatography(Gradient: 0% to 10% ethyl acetate in petroleum ether) provided theproduct as a colorless oil. By ¹H NMR, this product was somewhat impure,and consisted of a mixture of geometric isomers around the oxime. Yield:40.0 g, <254 mmol, <57% over 2 steps. ¹H NMR (400 MHz, CDCl₃), productpeaks only: δ [7.47 (t, J=5.4 Hz) and 6.88 (t, J=3.4 Hz), total 1H],5.90-5.76 (m, 1H), 5.09 (br s, 1H), 5.08-5.03 (m, 1H), [4.31 (d, J=3.6Hz) and 4.05 (d, J=5.5 Hz), total 2H], 2.27 (d, J=7.2 Hz, 2H), 1.19 (s,6H).

Step 3. Synthesis of5,5-dimethyl-3,3a,4,5-tetrahydro-7H-pyrano[3,4-c][1, 2]oxazole (C3)

Triethylamine (1.93 g, 19.1 mmol) was added to a solution of C2 (40.0 g,254 mmol) in dichloromethane (1.2 L) at room temperature (−15° C.).Aqueous sodium hypochlorite solution (5%, 1.2 L) was then slowly addedvia syringe while the internal reaction temperature was maintainedbetween 22° C. and 25° C. After completion of the addition, the organiclayer of the reaction was washed with saturated aqueous sodium chloridesolution (2×500 mL), dried over sodium sulfate, filtered, andconcentrated in vacuo. Silica gel chromatography (Gradient: 0% to 10%ethyl acetate in petroleum ether) afforded the product as a colorlessoil. Yield: 18 g, 120 mmol, 47%. LCMS m/z 155.7 [M+H]⁺. ¹H NMR (400 MHz,CDCl₃) δ 4.59 (dd, J=9.9, 7.9 Hz, 1H), 4.52 (d, half of AB quartet,J=14.0 Hz, 1H), 4.36 (br dd, half of ABX pattern, J=14.0, 0.8 Hz, 1H),3.75 (dd, J=11.6, 7.8 Hz, 1H), 3.62-3.50 (m, 1H), 2.05 (dd, J=13.0, 6.3Hz, 1H), 1.61 (dd, J=12, 12 Hz, 1H), 1.33 (s, 3H), 1.28 (s, 3H).

Step 4. Synthesis ofcis-7a-(4-bromo-1,3-thiazol-2-yl)-5,5-dimethylhexahydro-1H-pyrano[3,4-c][1,2]oxazole(C4)

Boron trifluoride diethyl etherate (12.9 mL, 102 mmol) was added to a−70° C. solution of 2,4-dibromo-1,3-thiazole (26.0 g, 107 mmol) intoluene (360 mL) and tetrahydrofuran (36 mL). n-Butyllithium (2.5 Msolution in hexanes; 40 mL, 100 mmol) was then added slowly, andstirring was continued for 30 minutes at −70° C., whereupon a solutionof C3 (12.8 g, 82.5 mmol) in toluene (40 mL) and tetrahydrofuran (4 mL)was added drop-wise. After an additional 15 minutes at −70° C., thereaction was quenched, still at −70° C., via addition of saturatedaqueous ammonium chloride solution (200 mL). The resulting mixture wasextracted with ethyl acetate (2×200 mL), and the combined organic layerswere washed with saturated aqueous sodium chloride solution (2×200 mL),dried over sodium sulfate, filtered, and concentrated in vacuo. Silicagel chromatography (Gradient: 0% to 15% ethyl acetate in petroleumether) provided the product as a yellow solid. Yield: 9.8 g, 31 mmol,38%. ¹H NMR (400 MHz, CDCl₃) δ 7.21 (s, 1H), 6.42 (br s, 1H), 4.10 (d,J=13.2 Hz, 1H), 3.80-3.68 (m, 3H), 3.47-3.35 (m, 1H), 1.76 (dd, J=14,6.5 Hz, 1H), 1.66-1.51 (m, 1H, assumed; partially obscured by waterpeak), 1.42 (s, 3H), 1.31 (s, 3H).

Step 5. Synthesis of[rel-(4R,5R)-5-amino-5-(4-bromo-1,3-thiazol-2-yl)-2,2-dimethyltetrahydro-2H-pyran-4-yl]methanol(C5)

Molybdenum hexacarbonyl (5.71 g, 21.6 mmol) was added to a solution ofC4 (13.8 g, 43.2 mmol) in acetonitrile (300 mL) and water (15 mL), andthe reaction mixture was heated at reflux for 1 hour. It was then cooledto 0° C., and treated portion-wise with sodium borohydride (3.27 g, 86.4mmol). After completion of the addition, the reaction mixture was warmedto 60° C. and stirred for 1 hour, whereupon it was filtered. Thefiltrate was concentrated under reduced pressure, and the residue wastreated with methanol (200 mL). This mixture was again concentrated invacuo, treated once more with methanol (200 mL), and concentrated again.The residue was dissolved in dichloromethane (300 mL), washedsequentially with aqueous sodium hydroxide solution (1 M, 2×250 mL) andsaturated aqueous sodium chloride solution (2×300 mL), dried over sodiumsulfate, filtered, and concentrated in vacuo to afford the product (13.9g) as a brown solid, which was used directly in the next step.

Step 6. Synthesis ofN-{[rel-(3R,4R)-3-(4-bromo-1,3-thiazol-2-yl)-4-(hydroxymethyl)-6,6-dimethyltetrahydro-2H-pyran-3-yl]carbamothioyl}benzamide(C6)

To a room temperature (15° C.) solution of C5 (from the previous step;13.9 g, ≦43.2 mmol) in dichloromethane (300 mL) was added benzoylisothiocyanate (9.18 g, 56.3 mmol), and the reaction mixture was stirredovernight at room temperature. After removal of solvent in vacuo, theresidue was recrystallized from dichloromethane/petroleum ether (5:1) toprovide the product as a brown solid. Yield: 12.0 g, 24.8 mmol, 57% over2 steps. LCMS m/z 483.8 [M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ 11.76 (br s,1H), 8.95 (br s, 1H), 7.92-7.86 (m, 2H), 7.68-7.62 (m, 1H), 7.54 (br dd,J=8.0, 7.4 Hz, 2H), 7.28 (s, 1H), 5.05 (d, J=12.4 Hz, 1H), 4.07 (d,J=12.3 Hz, 1H), 3.88-3.82 (m, 2H), 2.67-2.59 (m, 1H), 2.46-2.36 (m, 1H),2.01 (dd, J=13.8, 13.8 Hz, 1H), 1.69 (dd, J=14.1, 3.7 Hz, 1H), 1.39 (s,3H), 1.39 (s, 3H).

Step 7. Synthesis ofN-[cis-8a-(4-bromo-1,3-thiazol-2-yl)-6,6-dimethyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(C7)

Pyridine (100 mL) was added to a solution of C6 (10.0 g, 20.6 mmol) indichloromethane (200 mL), and the mixture was cooled to −30° C.Trifluoromethanesulfonic anhydride (17.5 g, 62.0 mmol) was slowly added;on completion of the addition, the reaction mixture was warmed to 0° C.over 10 minutes, and then poured into saturated aqueous ammoniumchloride solution (300 mL). The resulting mixture was extracted withdichloromethane (3×200 mL), and the combined organic layers were washedsequentially with water (3×200 mL) and saturated aqueous sodium chloridesolution (2×300 mL), dried over sodium sulfate, filtered, andconcentrated in vacuo to afford the product as a yellow solid. Yield:9.0 g, 19 mmol, 92%. ¹H NMR (400 MHz, CDCl₃) δ 8.15-8.02 (m, 2H),7.59-7.51 (m, 1H), 7.51-7.41 (m, 2H), 7.23 (s, 1H), 4.15 (d, J=12 Hz,1H), 3.71 (d, J=12 Hz, 1H), 3.28-3.12 (m, 2H), 2.62-2.52 (m, 1H),2.09-1.96 (m, 1H), 1.6-1.48 (m, 1H, assumed; partially obscured by waterpeak), 1.45 (s, 3H), 1.32 (s, 3H).

Step 8. Synthesis ofN-[cis-8a-{4-[(2,4-dimethoxybenzyl)amino]-1,3-thiazol-2-yl}-6,6-dimethyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(C8)

A mixture of tris(dibenzylideneacetone)dipalladium(0) (1.12 g, 1.22mmol), di-tert-butyl[2′,4′,6′-tri(propan-2-yl)biphenyl-2-yl]phosphane(1.56 g, 3.67 mmol), and sodium tert-butoxide (2.90 g, 30.2 mmol) in1,4-dioxane (100 mL) was stirred in a 95° C. bath for 12 minutes, untilthe internal reaction temperature reached 87° C. to 88° C. A solution ofC7 (5.70 g, 12.2 mmol) and 1-(2,4-dimethoxyphenyl)methanamine (4.09 g,24.5 mmol) in 1,4-dioxane (100 mL) was then added in one portion, andthe reaction mixture was stirred for 1.5 hours at an internaltemperature of 88° C. to 92° C. After removal of solvent in vacuo, theresidue was purified by silica gel chromatography (Gradient: 15% to 50%ethyl acetate in petroleum ether) to provide the product as a yellowsolid. Yield: 4.40 g, 7.96 mmol, 65%. LCMS m/z 553.1 [M+H]⁺.

Step 9. Synthesis ofN-[cis-8a-(4-amino-1,3-thiazol-2-yl)-6,6-dimethyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P1)

Concentrated hydrochloric acid (25 mL) was slowly added to an 8° C.solution of C8 (4.40 g, 7.96 mmol) in ethyl acetate (20 mL); once theaddition was complete, the reaction mixture was warmed to roomtemperature (20° C.) and stirred for 4 hours. It was then poured intowater (120 mL) and extracted with dichloromethane (3×150 mL). Thecombined organic layers were extracted with aqueous hydrochloric acid(2.5 M, 3×50 mL), and the combined acidic aqueous layers were slowlypoured into aqueous sodium hydroxide solution (5 M, 150 mL) at 0° C.This resulted in a final pH of approximately 11-12. The aqueous solutionwas saturated with solid sodium chloride and then extracted withdichloromethane (3×200 mL). These three dichloromethane layers werecombined and washed sequentially with aqueous citric acid solution (4.5%by weight, 2×80 mL), saturated aqueous sodium bicarbonate solution (200mL), and saturated aqueous sodium chloride solution (200 mL), dried oversodium sulfate, filtered, and concentrated in vacuo, affording theproduct as a yellow solid. Yield: 2.5 g, 6.2 mmol, 78%. LCMS m/z 402.9[M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ 8.26-8.08 (m, 2H), 7.56-7.48 (m, 1H),7.48-7.41 (m, 2H), 5.94 (s, 1H), 4.17 (d, J=12.6 Hz, 1H), 4.07 (br s,2H), 3.70 (d, J=12.6 Hz, 1H), 3.25 (dd, J=13, 4 Hz, 1H), 3.16 (br d,J=13 Hz, 1H), 2.54 (dd, J=12.9, 2.1 Hz, 1H), 2.04 (dd, J=13, 13 Hz, 1H),1.49 (dd, J=13.7, 4.0 Hz, 1H), 1.44 (s, 3H), 1.32 (s, 3H).

Preparation P2N-[(4aR,8aR)-8a-(4-Amino-1,3-thiazol-2-yl)-6,6-dimethyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P2)

Step 1. Isolation of (3aR)-5, 5-dimethyl-3,3a,4,5-tetrahydro-7H-pyrano[3,4-c][1, 2]oxazole (C9) and (3aS)-5,5-dimethyl-3,3a,4,5-tetrahydro-7H-pyrano[3,4-c][1,2]oxazole (C10)

Separation of C3 (710 g) into its component enantiomers was carried outvia supercritical fluid chromatography (Column: Chiral TechnologiesChiralpak IC, 10 μm; Mobile phase: 7:3 carbon dioxide/2-propanol).Compound C9 was the first-eluting enantiomer from the column, isolatedas a brown solid. Yield: 270 g, 38% for the isolation. Compound C10 wasthe second-eluting enantiomer from the column, also isolated as a brownsolid. Yield: 270 g, 38% for the isolation.

The indicated absolute stereochemistry for these two products wasassigned on the following basis. Compound C9 was used in the synthesisof 2 (note use of P2 in Alternate Synthesis of Example 2 below); thismaterial was correlated with the more potent enantiomer from Examples 1and 2 below via its biological activity. The absolute configuration ofthe potent enantiomer, and thereby C9, was assigned in analogy with thework reported by C. R. Butler et al., J. Med. Chem. 2015, 58, 2678-2702,and M. A. Brodney, J. Med. Chem. 2015, 58, 3223-3252.

C9: LCMS m/z 155.8 [M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ 4.59 (dd, J=9.9,7.9 Hz, 1H), 4.51 (d, half of AB quartet, J=14.0 Hz, 1H), 4.36 (dd, halfof ABX pattern, J=14.0, 1.2 Hz, 1H), 3.74 (dd, J=11.6, 7.8 Hz, 1H),3.62-3.49 (m, 1H), 2.05 (dd, J=12.9, 6.3 Hz, 1H), 1.60 (dd, J=12.4, 12.3Hz, 1H), 1.33 (s, 3H), 1.28 (s, 3H).

C10: LCMS m/z 155.8 [M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ 4.60 (dd, J=10.0,7.8 Hz, 1H), 4.52 (d, half of AB quartet, J=14.0 Hz, 1H), 4.36 (dd, halfof AB quartet, J=14.0, 1.4 Hz, 1H), 3.75 (dd, J=11.6, 7.8 Hz, 1H),3.63-3.49 (m, 1H), 2.06 (dd, J=12.8, 6.3 Hz, 1H), 1.61 (dd, J=12.3, 12.3Hz, 1H), 1.34 (s, 3H), 1.28 (s, 3H).

Step 2. Synthesis of(3aR,7aR)-7a-(4-bromo-1,3-thiazol-2-yl)-5,5-dimethylhexahydro-1H-pyrano[3,4-c][1,2]oxazole(C11)

Boron trifluoride diethyl etherate (3.00 mL, 23.7 mmol) was added to a−65° C. slurry of 2,4-dibromo-1,3-thiazole (5.63 g, 23.2 mmol) intoluene (50 mL). n-Butyllithium (2.5 M solution in hexanes; 10 mL, 25mmol) was then slowly added, and the reaction mixture was allowed tostir at −65° C. for 10 minutes. A solution of C9 (3.0 g, 19 mmol) intetrahydrofuran (5 mL) was added drop-wise, and stirring was continuedfor 30 minutes at −65° C., whereupon the reaction was quenched viaaddition of saturated aqueous ammonium chloride solution (150 mL) andthe mixture was warmed to −10° C. to 0° C. The aqueous layer wasextracted with ethyl acetate (2×100 mL), and the combined organic layerswere washed with saturated aqueous sodium chloride solution (2×100 mL),dried over sodium sulfate, filtered, and concentrated in vacuo. Silicagel chromatography (Gradient: 0% to 10% ethyl acetate in petroleumether) afforded the product as a yellow solid. Yield: 4.3 g, 13 mmol,68%. ¹H NMR (400 MHz, CDCl₃) δ 7.21 (5, 1H), 6.42 (s, 1H), 4.09 (d,J=13.0 Hz, 1H), 3.79-3.68 (m, 3H), 3.47-3.36 (m, 1H), 1.76 (dd, J=14.0,6.6 Hz, 1H), 1.57 (br dd, J=13, 13 Hz, 1H), 1.42 (s, 3H), 1.30 (s, 3H).

Step 3. Synthesis of tert-butyl {2-[(3aR,7aR)-5,5-dimethyltetrahydro-1H-pyrano[3,4-c][1,2]oxazol-7a(7H)-yl]-1,3-thiazol-4-yl}carbamate (C12)

A mixture of C11 (4.30 g, 13.5 mmol), tert-butyl carbamate (2.37 g, 20.2mmol), potassium phosphate (10 g, 47 mmol),tris(dibenzylideneacetone)dipalladium(0) (2.47 g, 2.70 mmol), anddi-tert-butyl[2′,4′,6′-tri(propan-2-yl)biphenyl-2-yl]phosphane (572 mg,1.35 mmol) in toluene (100 mL) was stirred at 115° C. for 18 hours.After the reaction mixture had cooled to room temperature, it wasfiltered through diatomaceous earth; the filter pad was washed withethyl acetate (200 mL), and the combined filtrates were concentratedunder reduced pressure. Chromatography on silica gel (Gradient: 0% to25% ethyl acetate in petroleum ether) provided the product as a yellowfoam. Yield: 2.95 g, 8.30 mmol, 61%. ¹H NMR (400 MHz, CDCl₃),characteristic peaks: δ 7.24 (br s, 1H), 7.15 (br s, 1H), 6.36 (s, 1H),4.03 (d, J=13.0 Hz, 1H), 3.79-3.69 (m, 3H), 3.33-3.23 (m, 1H), 1.72 (dd,half of ABX pattern, J=13.9, 6.5 Hz, 1H), 1.52 (s, 9H), 1.38 (s, 3H),1.30 (s, 3H).

Step 4. Synthesis of tert-butyl{2-[(3R,4R)-3-amino-4-(hydroxymethyl)-6,6-dimethyltetrahydro-2H-pyran-3-yl]-1,3-thiazol-4-yl}carbamate(C13)

Raney nickel (1.94 g, 33.0 mmol) was added to a solution of C12 (4.70 g,13.2 mmol) in 2-propanol (30 mL) and tetrahydrofuran (30 mL). Theresulting mixture was subjected to three cycles of degassing and beingcharged with hydrogen, and then stirred at 50° C. under a hydrogenballoon for 4 hours. After the reaction mixture had cooled to roomtemperature, it was combined with a similar reaction mixture carried outusing C12 (2.0 g, 5.6 mmol) and filtered through a pad of diatomaceousearth. The filter cake was washed with ethyl acetate (200 mL), and thecombined filtrates were concentrated in vacuo to provide the product asa yellow gum. Yield: 6.8 g, 19 mmol, quantitative. LCMS m/z 358.1[M+H]⁺.

Step 5. Synthesis of tert-butyl{2-[(4aR,8aR)-2-(benzoylamino)-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}carbamate(C14)

Benzoyl isothiocyanate (8.0 g, 49 mmol) was added in one portion to asolution of C13 (5.50 g, 15.4 mmol) in ethyl acetate (80 mL), and thereaction mixture was stirred at room temperature for 2 hours. It wasthen slowly warmed to 90° C. and stirred at that temperature for 16hours. After cooling to room temperature, the reaction mixture wasconcentrated in vacuo and subjected to two chromatographic purificationson silica gel (Column #1 gradient: 0% to 100% ethyl acetate in petroleumether; Column #2 gradients: 0% to 15% ethyl acetate in petroleum ether,followed by 0% to 10% ethyl acetate in dichloromethane) to afford theproduct as a pale yellow solid (2.7 g). Mixed fractions wererechromatographed on silica gel (Gradient: 0% to 10% ethyl acetate indichloromethane) to provide additional product as a pale yellow solid(2.0 g). Combined yield: 4.70 g, 9.35 mmol, 61%. LCMS m/z 525.2 [M+Na⁺].¹H NMR (400 MHz, CDCl₃) δ 8.19-8.08 (m, 2H), 7.56-7.50 (m, 1H), 7.45 (brdd, J=7.8, 7.3 Hz, 2H), 7.18 (br s, 1H), 4.11 (d, J=12.3 Hz, 1H), 3.71(d, J=12.3 Hz, 1H), 3.18 (dd, J=12.8, 4.3 Hz, 1H), 3.12-3.03 (m, 1H),2.54 (dd, J=12.9, 2.4 Hz, 1H), 2.04 (dd, J=13.6, 13.4 Hz, 1H), 1.52 (s,9H), 1.52-1.46 (m, 1H), 1.42 (s, 3H), 1.32 (s, 3H).

Step 6. Synthesis ofN-[(4aR,8aR)-8a-(4-amino-1,3-thiazol-2-yl)-6,6-dimethyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P2)

To a solution of C14 (535 mg, 1.06 mmol) in dichloromethane (4 mL) wasadded trifluoroacetic acid (3 mL). The reaction mixture was stirred at45° C. for 25 minutes, whereupon it was diluted with dichloromethane (30mL) and poured into saturated aqueous sodium bicarbonate solution (60mL) at room temperature. The resulting mixture was stirred for 5minutes, and the aqueous phase (pH 8) was extracted with dichloromethane(3×30 mL). The combined organic layers were dried over sodium sulfate,filtered, and concentrated in vacuo. The residue was treated with amixture of ethyl acetate and dichloromethane (1:1, 4 mL), stirred atroom temperature for 10 minutes, and left standing at room temperatureovernight. The solid was collected via filtration, afforded the productas a pale yellow solid. Yield: 360 mg, 0.894 mmol, 84%. LCMS m/z 403.2[M+H]⁺.

Preparation P3N-[(4aR,8aR)-8a-{4-[(2,4-Dimethoxybenzyl)amino]-1,3-thiazol-2-yl}-6,6-dimethyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P3)

Step 1. Synthesis of[(4R,5R)-5-amino-5-(4-bromo-1,3-thiazol-2-yl)-2,2-dimethyltetrahydro-2H-pyran-4-yl]methanol(C15)

Molybdenum hexacarbonyl (98%, 16.8 g, 62.4 mmol) was added to a solutionof C11 (39.76 g, 124.6 mmol) in a mixture of acetonitrile and water(20:1, 1 L). The reaction mixture was heated to reflux in a preheatedoil bath (100° C.) for 2 hours, whereupon it was cooled to roomtemperature and cooled in an ice bath. Sodium borohydride (9.42 g, 249mmol) was added portion-wise, and stirring was continued for 1 hour at0° C. The mixture was then filtered through diatomaceous earth, and thefilter pad was washed three times with dichloromethane; the combinedorganic filtrates were washed with saturated aqueous sodium chloridesolution, dried over sodium sulfate, filtered, and concentrated invacuo. After addition of methanol to the residue, the mixture wasconcentrated under reduced pressure. This methanol treatment andconcentration was repeated, and the resulting material was dissolved indichloromethane and washed twice with 1 M aqueous sodium hydroxidesolution, once with saturated aqueous sodium chloride solution, andconcentrated in vacuo, providing the product as a light brown solid,which was used directly in the following step. ¹H NMR (400 MHz, CDCl₃) δ7.20 (s, 1H), 3.98 (d, J=11.8 Hz, 1H), 3.69 (dd, J=11.4, 3.6 Hz, 1H),3.48 (dd, J=11.4, 4.0 Hz, 1H), 3.30 (d, J=11.8 Hz, 1H), 2.57 (dddd,J=13.4, 3.8, 3.8, 3.8 Hz, 1H), 2.6-2.2 (br s, 2H), 1.97 (dd, J=13.8,13.7 Hz, 1H), 1.55 (dd, J=13.9, 4.0 Hz, 1H, assumed; partially obscuredby water peak), 1.37 (s, 3H), 1.36 (s, 3H).

Step 2. Synthesis ofN-{[(3R,4R)-3-(4-bromo-1,3-thiazol-2-yl)-4-(hydroxymethyl)-6,6-dimethyltetrahydro-2H-pyran-3-yl]carbamothioyl}benzamide(C16)

Benzoyl isothiocyanate (16.7 mL, 124 mmol) was added to a solution ofC15 (material from the preceding step; 124.6 mmol) in dichloromethane(1.25 L), and the reaction mixture was stirred at room temperatureovernight. After the reaction mixture had been concentrated in vacuo,chromatography on silica gel (Gradient: 0% to 100% ethyl acetate inheptane) afforded the product as a pale yellow foam (40.6 g). Somewhatimpure C15 (8.0 g) was also recovered from the column. Yield: 40.6 g,84.3 mmol, 68% over 2 steps. LCMS m/z 484.2 [M+H]⁺. ¹H NMR (400 MHz,CDCl₃) δ 11.74 (br s, 1H), 8.91 (br s, 1H), 7.91-7.85 (m, 2H), 7.68-7.62(m, 1H), 7.57-7.50 (m, 2H), 7.26 (s, 1H), 5.04 (d, J=12.3 Hz, 1H), 4.07(d, J=12.3 Hz, 1H), 3.85 (dd, J=5.9, 4.6 Hz, 2H), 2.63 (dddd, J=13, 4,4, 4 Hz, 1H), 2.32 (t, J=6.0 Hz, 1H), 2.00 (dd, J=13.8, 13.8 Hz, 1H),1.68 (dd, J=14.1, 3.9 Hz, 1H), 1.39 (s, 3H), 1.38 (s, 3H).

Step 3. Synthesis ofN-[(4aR,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6,6-dimethyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(C17)

Trifluoromethanesulfonic acid (11.6 mL, 131 mmol) was rapidly added to asolution of C16 (21.54 g, 44.46 mmol) in 1,2-dichloroethane (300 mL) andmethoxybenzene (14.5 mL, 133 mmol), and the reaction mixture was stirredat room temperature for 30 minutes. It was then diluted withdichloromethane and basified via addition of 1 M aqueous sodiumhydroxide solution. The aqueous layer was extracted three times withdichloromethane, and the combined dichloromethane layers were washedwith saturated aqueous sodium chloride solution, dried over sodiumsulfate, filtered, and concentrated in vacuo. The residue was trituratedin heptane for 30 minutes to provide the product as a white solid.Yield: 18.18 g, 39.06 mmol, 88%. LCMS m/z 466.3, 468.2 [M+H]⁺. ¹H NMR(400 MHz, CD₃OD) δ 8.15-7.95 (br m, 2H), 7.61-7.53 (m, 2H), 7.52-7.44(m, 2H), 4.15 (d, J=11.9 Hz, 1H), 3.75 (br d, J=11.8 Hz, 1H), 3.20-3.10(m, 1H), 3.04 (dd, J=13.2, 4.2 Hz, 1H), 2.67 (br dd, J=13, 2.5 Hz, 1H),1.93 (dd, J=13.4, 13.3 Hz, 1H), 1.61 (dd, J=13.7, 4.0 Hz, 1H), 1.46 (s,3H), 1.30 (s, 3H).

Step 4. Synthesis ofN-[(4aR,8aR)-8a-{4-[(2,4-dimethoxybenzyl)amino]-1,3-thiazol-2-yl}-6,6-dimethyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P3)

A mixture of tris(dibenzylideneacetone)dipalladium(0) (96%, 2.07 g, 2.17mmol), di-tert-butyl[2′,4′,6′-tri(propan-2-yl)biphenyl-2-yl]phosphane(2.77 g, 6.52 mmol), and sodium tert-butoxide (10.5 g, 109 mmol) in1,4-dioxane (150 mL) was subjected to three cycles of evacuationfollowed by nitrogen fill; the resulting solution was heated at aninternal temperature of 85° C. to 90° C. (bath temperature 100° C.) for5 minutes. A solution of C17 (20.29 g, 43.50 mmol) and1-(2,4-dimethoxyphenyl)methanamine (11.1 mL, 73.9 mmol) in 1,4-dioxane(48 mL) was added, and the reaction mixture was heated at an internaltemperature of approximately 90° C. for 10 minutes, whereupon it wascooled and partitioned between saturated aqueous sodium bicarbonatesolution and dichloromethane. The aqueous layer was extracted twice withdichloromethane, and the combined organic layers were washed withsaturated aqueous sodium chloride solution, dried over sodium sulfate,filtered, and concentrated in vacuo. Silica gel chromatography (Eluent:1:1 ethyl acetate/heptane) afforded the product as an amber foam. By ¹HNMR, this material contained a small amount of ethyl acetate. Yield:25.0 g, quantitative. LCMS m/z 553.2 [M+H]⁺. ¹H NMR (400 MHz, CDCl₃),characteristic peaks: δ 8.17 (br d, J=7.5 Hz, 2H), 7.55-7.48 (m, 1H),7.47-7.41 (m, 2H), 7.21 (d, J=8.2 Hz, 1H), 6.48 (d, half of AB quartet,J=2.4 Hz, 1H), 6.45 (dd, half of ABX pattern, J=8.3, 2.4 Hz, 1H), 5.73(s, 1H), 4.21 (br s, 2H), 4.17 (d, J=12.6 Hz, 1H), 3.85 (s, 3H), 3.81(s, 3H), 3.26 (dd, J=12.9, 4.2 Hz, 1H), 3.19-3.12 (m, 1H), 2.52 (dd,J=12.9, 2.7 Hz, 1H), 2.05 (dd, J=13.5, 13.4 Hz, 1H), 1.48 (dd, J=13.8,4.2 Hz, 1H), 1.42 (s, 3H), 1.31 (s, 3H).

Preparation P4N-[cis-8a′-{4-[(2,4-Dimethoxybenzyl)amino]-1,3-thiazol-2-yl}-4a′,5′,8′,8a′-tetrahydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-2′-yl]benzamide(P4)

Step 1. Synthesis of 1-(prop-2-en-1-yl)cyclobutanol (C18)

Allylmagnesium chloride (2.0 M solution in tetrahydrofuran; 85.6 mL, 171mmol) was added in a drop-wise manner to a 0° C. solution ofcyclobutanone (6.00 g, 85.6 mmol) in tetrahydrofuran (60 mL). Thereaction mixture was stirred at 0° C. for 1 hour and then at roomtemperature for 1 hour, whereupon saturated aqueous ammonium chloridesolution (150 mL) was added, followed by aqueous hydrochloric acid (6 M,25 mL). The resulting mixture was extracted with ethyl acetate (3×100mL), and the combined organic layers were washed with saturated aqueoussodium bicarbonate solution (3×150 mL) until a basic pH was observed forthe aqueous layer. The organic layer was washed with saturated aqueoussodium chloride solution (150 mL), dried over sodium sulfate, filtered,concentrated in vacuo, and adsorbed onto silica gel. Chromatography onsilica gel (Gradient: 0% to 60% ethyl acetate in heptane) provided theproduct as a colorless oil. Yield: 5.13 g, 45.7 mmol, 53%. ¹H NMR (400MHz, CDCl₃) δ 5.94-5.83 (m, 1H), 5.22-5.20 (m, 1H), 5.20-5.16 (m, 1H),2.39 (br d, J=7.2 Hz, 2H), 2.10-2.04 (m, 4H), 1.81-1.71 (m, 1H),1.61-1.49 (m, 1H).

Step 2. Synthesis of1-(2,2-dimethoxyethoxy)-1-(prop-2-en-1-yl)cyclobutane (C19)

To a suspension of sodium hydride (60% in mineral oil; 3.84 g, 96.0mmol) in 1,4-dioxane (60 mL) was added C18 (5.13 g, 45.7 mmol) in adrop-wise manner. After the reaction mixture had been stirred for 45minutes at room temperature, 2-bromo-1,1-dimethoxyethane (10.8 mL, 91.4mmol) was slowly added, and the reaction mixture was heated at 100° C.for 16 hours, whereupon it was cooled and poured into ice water (800mL). The resulting mixture was extracted with ethyl acetate (3×150 mL),and the combined organic layers were washed with saturated aqueoussodium chloride solution (2×200 mL), dried over sodium sulfate,filtered, and concentrated in vacuo. Chromatography on silica gel(Gradient: 0% to 70% ethyl acetate in heptane) afforded the product as acolorless oil. Yield: 3.45 g, 17.2 mmol, 38%. ¹H NMR (400 MHz, CDCl₃) δ5.91-5.80 (m, 1H), 5.17-5.12 (m, 1H), 5.12-5.08 (m, 1H), 4.46 (t, J=5.2Hz, 1H), 3.40 (s, 6H), 3.36 (d, J=5.2 Hz, 2H), 2.41 (br d, J=7.0 Hz,2H), 2.17-2.07 (m, 2H), 1.97-1.89 (m, 2H), 1.80-1.70 (m, 1H), 1.61-1.48(m, 1H).

Step 3. Synthesis ofN-hydroxy-2-{[1-(prop-2-en-1-yl)cyclobutyl]oxy}ethanimine (C20)

Hydroxylamine hydrochloride (1.72 g, 24.8 mmol) was added to a solutionof C19 (3.45 g, 17.2 mmol) in ethanol (28 mL) and water (5 mL). Thereaction mixture was heated to 70° C. for 90 minutes, whereupon it wascooled to room temperature and treated with a solution of sodium acetate(97%, 2.91 g, 34.4 mmol) in water (5 mL). The resulting mixture wasstirred at room temperature for 10 minutes and concentrated in vacuo;the residue was partitioned between dichloromethane (100 mL) and water(150 mL). The aqueous layer was extracted with dichloromethane (2×150mL), and the combined organic layers were washed with saturated aqueoussodium chloride solution (300 mL), dried over sodium sulfate, filtered,and concentrated under reduced pressure to afford the product as acolorless oil. By ¹H NMR, this material was judged to be a mixture ofgeometric isomers around the oxime. Yield: 2.72 g, 16.1 mmol, 94%. ¹HNMR (400 MHz, CDCl₃) δ [7.49 (t, J=5.6 Hz) and 6.90 (br t, J=3 Hz),total 1H], 5.90-5.77 (m, 1H), 5.18-5.14 (m, 1H), 5.14-5.10 (m, 1H),[4.23 (br d, J=3.5 Hz) and 3.99 (d, J=5.5 Hz), total 2H], 2.43 (br d,J=7 Hz, 2H), 2.18-2.07 (m, 2H), 2.00-1.92 (m, 2H), 1.83-1.73 (m, 1H),1.65-1.51 (m, 1H).

Step 4. Synthesis of3a′,4′-dihydro-3′H,7′H-spiro[cyclobutane-1,5′-pyrano[3,4-c][1,2]oxazole](C21)

Sodium hypochlorite solution (5.6-6%, 21.2 mL, 18 mmol) was added in adrop-wise manner to a solution of C20 (2.72 g, 16.1 mmol) indichloromethane (76 mL) at an internal temperature of −10° C., at a ratesuch that the internal temperature of the reaction never rose above 0°C. After completion of the addition, the reaction mixture was stirred at−10° C. for 3 hours, whereupon it was allowed to warm slowly to roomtemperature over 16 hours. The reaction mixture was diluted with water(500 mL), and the aqueous layer was extracted with dichloromethane(2×250 mL). The combined organic layers were washed with saturatedaqueous sodium chloride solution (500 mL), dried over sodium sulfate,filtered, and adsorbed onto silica gel. Chromatography on silica gel(Gradient: 0% to 80% ethyl acetate in heptane) provided the product as acolorless oil. Yield: 2.06 g, 12.3 mmol, 76%. ¹H NMR (400 MHz, CDCl₃) δ4.60 (dd, J=10.2, 7.9 Hz, 1H), 4.52 (d, J=13.6 Hz, 1H), 4.20 (dd,J=13.6, 1.3 Hz, 1H), 3.80 (dd, J=11.6, 7.9 Hz, 1H), 3.52-3.40 (m, 1H),2.40 (dd, J=12.9, 6.3 Hz, 1H), 2.30-2.20 (m, 1H), 2.19-2.02 (m, 2H),2.00-1.83 (m, 2H), 1.76-1.57 (m, 2H).

Step 5. Synthesis ofcis-7a′-(4-bromo-1,3-thiazol-2-yl)tetrahydro-1′H,3′H-spiro[cyclobutane-1,5′-pyrano[3,4-c][1,2]oxazole](C22)

To a −76° C. (internal temperature) solution of 2,4-dibromo-1,3-thiazole(3.78 g, 15.6 mmol) in a mixture of toluene and tetrahydrofuran (10:1,80 mL) was added boron trifluoride diethyl etherate (1.85 mL, 14.6mmol), followed by drop-wise addition of n-butyllithium (2.5 M solutionin hexanes; 5.74 mL, 14.4 mmol). The internal temperature of thereaction mixture was maintained below −70° C. throughout both of theseadditions. The reaction mixture was then stirred at −76° C. (internaltemperature) for 30 minutes, whereupon a solution of C21 (2.0 g, 12.0mmol) in a mixture of toluene and tetrahydrofuran (10:1, 6 mL) wasadded. Additional toluene/tetrahydrofuran (10:1, 6 mL) was used to rinsethe C21 flask; this was also added to the reaction mixture. Stirring wascontinued at −76° C. for 1 hour, at which time the reaction was quenchedvia addition of saturated aqueous ammonium chloride solution (200 mL)and then allowed to warm to room temperature. The resulting mixture waspartitioned between ethyl acetate (200 mL) and water (500 mL); theorganic layer was washed with saturated aqueous sodium chloride solution(300 mL), dried over sodium sulfate, filtered, and concentrated underreduced pressure. Chromatography on silica gel (Gradient: 0% to 80%ethyl acetate in heptane) afforded the product as a yellow solid. Yield:3.32 g, 10.0 mmol, 83%. LCMS m/z 331.3, 333.2 [M+H]⁺. ¹H NMR (400 MHz,CDCl₃) δ 7.21 (s, 1H), 3.96 (d, J=12.8 Hz, 1H), 3.76-3.70 (m, 3H),3.41-3.34 (m, 1H), 2.31-2.09 (m, 4H), 2.02-1.93 (m, 1H), 1.91-1.80 (m,1H), 1.74-1.59 (m, 2H).

Step 6. Synthesis of[rel-(7R,8R)-7-amino-7-(4-bromo-1,3-thiazol-2-yl)-5-oxaspiro[3.5]non-8-yl]methanol(C23)

Conversion of C22 to C23 was carried out according to the proceduredescribed for synthesis of C15 from C11 in Preparation P3. The productwas isolated as an orange solid. Yield: 3.2 g, 9.6 mmol, 96%. ¹H NMR(400 MHz, CDCl₃), characteristic peaks: δ 7.20 (s, 1H), 3.75 (d, J=11.5Hz, 1H), 3.70 (dd, J=11.4, 3.7 Hz, 1H), 3.51 (dd, J=11.4, 3.9 Hz, 1H),3.30 (d, J=11.5 Hz, 1H), 2.49-2.41 (m, 1H), 2.27-1.80 (m, 6H), 1.74-1.61(m, 1H).

Step 7. Synthesis ofN-{[rel-(7R,8R)-7-(4-bromo-1,3-thiazol-2-yl)-8-(hydroxymethyl)-5-oxaspiro[3.5]non-7-yl]carbamothioyl}benzamide(C24)

To a solution of C23 (2.2 g, 6.6 mmol) in dichloromethane (100 mL) wasadded benzoyl isothiocyanate (0.938 mL, 6.98 mmol). The reaction mixturewas stirred at room temperature for 16 hours, whereupon it wasconcentrated in vacuo to provide the product as a yellow solid (3.3 g).This material was used directly in the following step.

Step 8. Synthesis ofN-[cis-8a′-(4-bromo-1,3-thiazol-2-yl)-4a′,5′,8′,8a′-tetrahydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-2′-yl]benzamide(C25)

Trifluoromethanesulfonic acid (1.74 mL, 19.7 mmol) was rapidly added toa mixture of C24 (from the previous step, 3.3 g, mmol) andmethoxybenzene (2.17 mL, 20.0 mmol) in 1,2-dichloroethane (44 mL). Thereaction mixture was stirred at room temperature for 30 minutes,whereupon it was diluted with dichloromethane (100 mL) and treated with1 M aqueous sodium hydroxide solution (150 mL). The resulting biphasicmixture was stirred at room temperature for 15 minutes, at which timethe aqueous layer was extracted with dichloromethane (2×100 mL); thecombined organic layers were washed with saturated aqueous sodiumchloride solution (250 mL), dried over sodium sulfate, filtered, andconcentrated in vacuo. The resulting yellow solid was triturated withheptane (15 mL) to afford the product (1.08 g) as a white solid. Thefiltrate from the trituration was concentrated under reduced pressure,dissolved in a mixture of dichloromethane and methanol (9:1), andadsorbed onto silica gel. Chromatography on silica gel (Gradient: 0% to70% ethyl acetate in heptane) provided an off-white solid, which wastriturated with heptane to provide additional product (0.77 g) as awhite solid. Combined yield: 1.85 g, 3.87 mmol, 59% over 2 steps. ¹H NMR(400 MHz, CDCl₃) δ 8.24-7.88 (br s, 2H), 7.60-7.52 (m, 1H), 7.52-7.40(m, 2H), 7.23 (s, 1H), 3.82 (AB quartet, downfield doublet is broadened,J_(AB)=11.6 Hz, Δν_(AB)=85.4 Hz, 2H), 3.23-3.14 (m, 1H), 3.14-3.02 (m,1H), 2.61 (br d, J=12.5 Hz, 1H), 2.31-2.11 (m, 3H), 2.11-1.95 (m, 2H),1.93-1.80 (m, 2H), 1.75-1.61 (m, 1H).

Step 9. Synthesis ofN-[cis-8a′-{4-[(2,4-dimethoxybenzyl)amino]-1,3-thiazol-2-yl}-4a′,5′,8′,8a′-tetrahydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-2′-yl]benzamide(P4)

A mixture of tris(dibenzylideneacetone)dipalladium(0) (96%, 99.7 mg,0.105 mmol),di-tert-butyl[2′,4′,6′-tri(propan-2-yl)biphenyl-2-yl]phosphane (0.133 g,0.313 mmol), and sodium tert-butoxide (0.502 g, 5.22 mmol) was purgedtwice with nitrogen; 1,4-dioxane (9.5 mL) was then added, and theresulting solution was heated to an internal temperature of 85° C. for 5minutes. A solution of C25 (1.00 g, 2.09 mmol) in 1,4-dioxane (5 mL) wasthen added, as was 1-(2,4-dimethoxyphenyl)methanamine (0.534 mL, 3.55mmol), and the reaction mixture was heated at an internal temperature of85° C. for 10 minutes. It was then removed from the oil bath and quicklycooled to room temperature by immersion of the reaction flask in a waterbath. Diatomaceous earth (4 spoonfuls) was added to the reactionmixture, followed by addition of water (50 mL), and the resultingmixture was filtered through a pad of diatomaceous earth usingdichloromethane to transfer the mixture. The filter pad was washed withadditional dichloromethane (3×100 mL); the resulting aqueous layerexhibited a pH of 12. The organic layer of the filtrate was washed withwater (2×300 mL) until the aqueous wash was found to have a neutral pH.At this point, the organic layer was washed sequentially with aqueouscitric acid (5%, 2×300 mL), saturated aqueous sodium bicarbonatesolution (2×300 mL), and saturated aqueous sodium chloride solution (500mL), dried over sodium sulfate, and filtered. The filtrate was adsorbedonto silica gel and subjected to chromatography on silica gel [Gradient:20% to 100% (5% triethylamine in ethyl acetate) in heptane], affordingthe product as an orange solid. Yield: 651 mg, 1.15 mmol, 55%. LCMS m/z565.5 [M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ 8.15 (br d, J=7 Hz, 2H),7.55-7.47 (m, 1H), 7.47-7.40 (m, 2H), 7.20 (d, J=8.2 Hz, 1H), 6.48 (d,half of AB quartet, J=2.3 Hz, 1H), 6.45 (dd, half of ABX pattern, J=8.2,2.4 Hz, 1H), 5.73 (s, 1H), 4.75-4.60 (br s, 1H), 4.20 (br s, 2H), 3.94(d, J=12.1 Hz, 1H), 3.85 (s, 3H), 3.81 (s, 3H), 3.70 (br d, J=12 Hz,1H), 3.27 (br dd, J=13, 4 Hz, 1H), 3.06-2.97 (m, 1H), 2.56 (br dd, J=13,2.5 Hz, 1H), 2.29-1.94 (m, 5H), 1.92-1.78 (m, 2H), 1.73-1.60 (m, 1H).

Preparation P5N-[(4aR,8a′R)-8a′-{4-[(2,4-Dimethoxybenzyl)amino]-1,3-thiazol-2-yl}-4a′,5′,8′,8a′-tetrahydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-2′-yl]benzamide(P5)

Step 1. Synthesis ofN-[(4aR,8a′R)-8a′-(4-bromo-1,3-thiazol-2-yl)-4a′,5′,8′,8a′-tetrahydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-2′-yl]benzamide(C26) andN-[(4a′S,8a′S)-8a′-(4-bromo-1,3-thiazol-2-yl)-4a′,5′,8′,8a′-tetrahydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-2′-yl]benzamide(C27)

A solution of C24 (1.50 g, 3.02 mmol) in 1,2-dichloroethane (20 mL) wastreated with methoxybenzene (0.984 mL, 9.05 mmol), followed by additionof trifluoromethanesulfonic acid (0.791 mL, 8.93 mmol) in one portion. Agum-like solid formed around the bottom of the flask, and stirring hadto be monitored; it is best to use a large stir bar and a slow rate ofstirring. The reaction mixture was allowed to stir at room temperaturefor 30 minutes, whereupon it was diluted with dichloromethane (100 mL)and treated with aqueous sodium hydroxide solution (1 M, 150 mL). Theresulting biphasic solution was stirred at room temperature for 15minutes, at which time the aqueous layer, which was found to exhibit apH of 12, was extracted with dichloromethane (2×100 mL). The combinedorganic layers were washed with saturated aqueous sodium chloridesolution (250 mL), dried over sodium sulfate, filtered, and concentratedin vacuo. The residue was triturated with heptane (15 mL); the resultingmaterial was washed with heptane (2×10 mL) to provide the racemicproduct as a white solid. Yield: 1.07 g, 2.24 mmol, 74%. NMR of racemicmaterial (C25): ¹H NMR (400 MHz, CDCl₃) δ 8.14-7.99 (br s, 2H),7.59-7.51 (m, 1H), 7.51-7.42 (m, 2H), 7.23 (s, 1H), 3.82 (AB quartet,J_(AB)=11.8 Hz, Δν_(AB)=85.4 Hz, 2H), 3.18 (br dd, J=13, 4 Hz, 1H),3.14-3.04 (m, 1H), 2.65-2.57 (m, 1H), 2.31-1.95 (m, 5H), 1.92-1.81 (m,2H), 1.74-1.61 (m, 1H).

This racemic product was separated into its component enantiomers viasupercritical fluid chromatography (Column: Phenomenex Lux Cellulose-3,5 μm; Mobile phase: 4:1 carbon dioxide/methanol). The first-elutingenantiomer was assigned as C26; yield: 348 mg, 33% for chiralseparation. The second-eluting enantiomer was assigned as C27; yield:480 mg, 45% for chiral separation. The indicated absolutestereochemistry was assigned on the basis of the conversion of C26 (viaP5) to Example 6; the potent biological activity of this compound (seeTable 2) was consistent with the given structure (see discussion underIsolation of C9 and C10 in Preparation P2 above.

Step 2. Synthesis ofN-[(4aR,8a′R)-8a′-{4-[(2,4-dimethoxybenzyl)amino]-1,3-thiazol-2-yl}-4a′,5′,8′,8a′-tetrahydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-2′-yl]benzamide(P5)

Conversion of C26 to P5 was effected via the method described forsynthesis of P4 from C25 in Preparation P4. The product was isolated asan orange solid. Yield: 361 mg, 0.639 mmol, 90%. ¹H NMR (400 MHz, CDCl₃)δ 8.15 (d, J=7.2 Hz, 2H), 7.54-7.48 (m, 1H), 7.47-7.40 (m, 2H), 7.20 (d,J=8.2 Hz, 1H), 6.48 (d, half of AB quartet, J=2.4 Hz, 1H), 6.45 (dd,half of ABX pattern, J=8.3, 2.4 Hz, 1H), 5.73 (s, 1H), 4.74-4.60 (br s,1H), 4.21 (br s, 2H), 3.94 (d, J=12.1 Hz, 1H), 3.85 (s, 3H), 3.81 (s,3H), 3.70 (d, J=12.2 Hz, 1H), 3.27 (dd, J=12.9, 4.1 Hz, 1H), 3.06-2.97(m, 1H), 2.56 (dd, J=12.9, 2.7 Hz, 1H), 2.29-2.03 (m, 4H), 2.03-1.95 (m,1H), 1.91-1.78 (m, 2H), 1.73-1.60 (m, 1H).

Preparation P6, P7, P8, and P9N-[(4aR,6S,8aR)-8a-{4-[(2,4-Dimethoxybenzyl)amino]-1,3-thiazol-2-yl}-6-ethyl-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P6),N-[(4aS,6S,8aS)-8a-{4-[(2,4-Dimethoxybenzyl)amino]-1,3-thiazol-2-yl}-6-ethyl-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P7),N-[(4aR,6R,8aR)-8a-{4-[(2,4-Dimethoxybenzyl)amino]-1,3-thiazol-2-yl}-6-ethyl-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P8), andN-[(4aS,6R,8aS)-8a-{4-[(2,4-Dimethoxybenzyl)amino]-1,3-thiazol-2-yl}-6-ethyl-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P9)

Step 1. Synthesis ofN-[cis-8a-(4-bromo-1,3-thiazol-2-yl)-6-ethyl-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(C29)

1-Chloro-N,N,2-trimethylprop-1-en-1-amine (197 mg, 1.47 mmol) was addedin a drop-wise manner to a solution of C28[rel-N-{[(3R,4R)-3-(4-bromo-1,3-thiazol-2-yl)-6-ethyl-4-(hydroxymethyl)-6-methyltetrahydro-2H-pyran-3-yl]carbamothioyl}benzamide; synthesized inanalogous fashion to C6 in Preparation P1, by using3-methylhex-5-en-3-ol and 1,1-diethoxy-2-iodoethane in the first step,rather than 2-methylpent-4-en-2-ol and 2-bromo-1,1-diethoxyethane] (245mg, 0.492 mmol) in dichloromethane (5 mL). After the reaction mixturehad stirred at room temperature for 1 hour, it was partitioned betweendichloromethane and saturated aqueous sodium bicarbonate solution. Theorganic layer was washed with saturated aqueous sodium chloridesolution, dried over sodium sulfate, filtered, and adsorbed onto silicagel. Chromatography on silica gel (Gradient: 0% to 100% ethyl acetate inheptane) provided the product. By ¹H NMR analysis, this materialconsisted of a mixture of diastereomers, and contained some impurities.Yield: 145 mg, <0.302 mmol, <61%. LCMS m/z 482.0 (bromine isotopepattern observed) [M+H]⁺. ¹H NMR (400 MHz, CDCl₃), characteristicproduct peaks: δ 8.09 (br d, J=7.6 Hz, 2H), 7.56-7.50 (m, 1H), 7.49-7.41(m, 2H), 7.23-7.21 (m, 1H), [4.13 (d, J=12.3 Hz) and 4.03 (d, J=12.3Hz), total 1H], 3.73-3.64 (m, 1H), 3.27-3.09 (m, 2H), 2.61-2.52 (m, 1H),2.02-1.90 (m, 1H), 1.65-1.50 (m, 2H), [1.37 (s) and 1.21 (s), total 3H].

Step 2. Synthesis of N-[(4aR,6S,8aR)-8a-{4-[(2,4-dimethoxybenzyl)amino]-1,3-thiazol-2-yl}-6-ethyl-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P6),N-[(4aS,6S,8aS)-8a-{4-[(2,4-dimethoxybenzyl)amino]-1,3-thiazol-2-yl}-6-ethyl-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P7),N-[(4aR,6R,8aR)-8a-{4-[(2,4-dimethoxybenzyl)amino]-1,3-thiazol-2-yl}-6-ethyl-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P8), andN-[(4aS,6R,8aS)-8a-{4-[(2,4-dimethoxybenzyl)amino]-1,3-thiazol-2-yl}-6-ethyl-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P9)

Conversion of C29 to a mixture of the products was carried out using themethod described for synthesis of P4 from C25 in Preparation P4. Thechromatographed product was subjected to supercritical fluidchromatography (Column: Phenomenex Lux Cellulose-3, 5 μm; Mobile phase:65:35 carbon dioxide/(methanol containing 0.2% ammonium hydroxide) toseparate the isomers of the product. In order of elution from thesupercritical fluid chromatography:

P6: Yield: 60 mg, 0.11 mmol, 5%.

P7: Yield: 50 mg, 88 μmol, 4%.

P8: Yield: 90 mg, 0.16 mmol, 8%.

P9: Yield: 93 mg, 0.16 mmol, 8%.

The indicated absolute stereochemistry was assigned after each of theseproducts was converted to the corresponding Example (i.e., Examples 8,26, 27, and 28). See Example 8 for discussion.

Preparation P10N-[(4aR,8aR)-8a-(4-Bromo-1,3-thiazol-2-yl)-6,6-bis(hydroxymethyl)-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P10)

Step 1. Synthesis of(3aR,5R,7aR)-5-[(benzyloxy)methyl]-7a-(4-bromo-1,3-thiazol-2-yl)hexahydro-1H-pyrano[3,4-c][1,2]oxazole(C31)

To a −70° C. solution of 2,4-dibromo-1,3-thiazole (57.5 g, 237 mmol) intoluene (1 L) and tetrahydrofuran (100 mL) was added boron trifluoridediethyl etherate (28.6 mL, 226 mmol, followed by slow addition ofn-butyllithium (2.5 M solution in hexanes; 87.3 mL, 218 mmol). After thereaction mixture had stirred for 30 minutes at −70° C., a solution ofC30[(3aR,5R)-5-[(benzyloxy)methyl]-3,3a,4,5-tetrahydro-7H-pyrano[3,4-c][1,2]oxazole;this material was prepared using the method of C. R. Butler et al., J.Med. Chem. 2015, 58, 2678-2702] (45.0 g, 182 mmol) in toluene (100 mL)and tetrahydrofuran (10 mL) was added drop-wise, and stirring wascontinued for 40 minutes at −70° C. Saturated aqueous ammonium chloridesolution (200 mL) was added to the −70° C. reaction mixture, which wasthen allowed to warm to room temperature over 16 hours. The aqueouslayer was extracted with ethyl acetate (2×200 mL), and the combinedorganic layers were washed with saturated aqueous sodium chloridesolution (2×1 L), dried over sodium sulfate, and concentrated underreduced pressure. The residue was combined with the crude products fromtwo similar reactions carried out using C30 (30 g, 120 mmol and 45.0 g,182 mmol) and purified via chromatography on silica gel (Gradient: 10%to 100% ethyl acetate in petroleum ether), providing the product (100 g)as a yellow solid. Yield: 100 g, 243 mmol, 50%. Also isolated from thecolumn was an impure batch of the product: 60 g, 60% purity by ¹H NMR,88 mmol. ¹H NMR (400 MHz, CDCl₃) δ 7.41-7.28 (m, 5H), 7.23 (s, 1H), 4.59(AB quartet, J_(AB)=12.3 Hz, Δν_(AB)=10.7 Hz, 2H), 4.07-3.97 (m, 2H),3.88-3.79 (m, 1H), 3.76 (br d, half of AB quartet, J=7.5 Hz, 1H),3.73-3.67 (m, 1H), 3.59-3.46 (m, 2H), 3.44-3.36 (m, 1H), 1.88 (br dd,J=13.5, 7 Hz, 1H), 1.61-1.47 (m, 1H).

Step 2. Synthesis of[(2R,4R,5R)-5-amino-2-[(benzyloxy)methyl]-5-(4-bromo-1,3-thiazol-2-yl)tetrahydro-2H-pyran-4-yl]methanol(C32)

Molybdenum hexacarbonyl (11.6 g, 43.9 mmol) was added to a solution ofC31 (60 g, 60% purity by ¹H NMR, 88 mmol) in acetonitrile (500 mL) andwater (25 mL). The reaction mixture was heated at reflux for two hours,then cooled to 0° C. and treated with sodium borohydride (6.62 g, 175mmol). The mixture was stirred at room temperature for 16 hours,whereupon it was filtered; the filtrate was concentrated under reducedpressure, dissolved in methanol (500 mL), stirred for 10 minutes, andconcentrated once again. The residue was again dissolved in methanol(500 mL), stirred for 10 minutes, and concentrated. The resultingmaterial was dissolved in dichloromethane (1.5 L), washed sequentiallywith aqueous sodium hydroxide solution (1 M, 1.0 L) and saturatedaqueous sodium chloride solution (2×1 L), dried over sodium sulfate,filtered, and concentrated in vacuo, providing the product (36.2 g) as abrown solid. This material was taken directly to the following step.

Step 3. Synthesis ofN-{[(3R,4R,6R)-6-[(benzyloxy)methyl]-3-(4-bromo-1,3-thiazol-2-yl)-4-(hydroxymethyl)tetrahydro-2H-pyran-3-yl]carbamothioyl}benzamide(C33)

Benzoyl isothiocyanate (15.7 g, 96.2 mmol) was added to a solution ofC32 (from the previous step, 88 mmol) in dichloromethane (800 mL), andthe mixture was stirred for 16 hours at 20° C. The reaction mixture wasthen concentrated in vacuo, and the residue was combined with the crudeproduct from a similar two-step reaction sequence carried out using C31(100 g, 243 mmol). Silica gel chromatography (Gradient: 15% to 100%ethyl acetate in petroleum ether) provided the product as a brown solid.Yield: 120 g, 208 mmol, 63% over 2 steps. ¹H NMR (400 MHz, CDCl₃) δ11.72 (br s, 1H), 8.93 (br s, 1H), 7.85 (br d, J=8.5 Hz, 2H), 7.65 (brdd, J=7.4, 7.4 Hz, 1H), 7.53 (br dd, J=8.0, 7.4 Hz, 2H), 7.38-7.28 (m,5H), 7.25 (s, 1H), 5.55 (d, J=12.0 Hz, 1H), 4.59 (AB quartet,J_(AB)=12.0 Hz, Δν_(AB)=19.4 Hz, 2H), 3.94 (d, J=11.9 Hz, 1H), 3.94-3.86(m, 1H), 3.86-3.78 (m, 2H), 3.67 (dd, half of ABX pattern, J=10.3, 6.2Hz, 1H), 3.54 (dd, half of ABX pattern, J=10.4, 4.3 Hz, 1H), 2.52-2.43(m, 1H), 2.25-2.15 (br s, 1H), 2.00-1.83 (m, 2H).

Step 4. Synthesis ofN-[(4aR,6R,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-(hydroxymethyl)-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(C34)

A solution of C33 (80.0 g, 139 mmol) in 1,2-dichloroethane (1.2 L) wastreated with methoxybenzene (45 mL, 410 mmol) and heated to 60° C.Trifluoromethanesulfonic acid (36 mL, 410 mmol) was added, and stirringwas continued at 60° C. for 1 hour. The reaction mixture was then cooledto 22° C. and partitioned between dichloromethane (1 L) and saturatedaqueous sodium bicarbonate solution (1.5 L); the organic layer waswashed with saturated aqueous sodium chloride solution (2×1 L), driedover sodium sulfate, filtered, and concentrated in vacuo. Silica gelchromatography (Gradient: 25% to 75% ethyl acetate in petroleum ether)afforded the product as a yellow solid. Yield: 45.5 g, 97.1 mmol, 70%.¹H NMR (400 MHz, CDCl₃) δ 8.12-7.97 (m, 2H), 7.57 (br dd, J=7.3, 7.3 Hz,1H), 7.48 (br dd, J=7.8, 7.2 Hz, 2H), 7.25 (s, 1H), 3.99 (AB quartet,J_(AB)=11.7 Hz, Δν_(AB)=7.4 Hz, 2H), 3.86-3.77 (m, 1H), 3.70 (br dd,half of ABX pattern, J=11.7, 2.9 Hz, 1H), 3.64 (dd, half of ABX pattern,J=11.8, 7.2 Hz, 1H), 3.19-3.09 (m, 2H), 2.67-2.60 (m, 1H), 2.00-1.87 (m,1H), 1.65-1.55 (m, 1H, assumed; partially obscured by water peak).

Step 5. Synthesis ofN-[(4aR,6R,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-formyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(C35)

Dess-Martin periodinane[1,1,1-tris(acetyloxy)-1,1-dihydro-1,2-benziodoxol-3-(1H)-one] (34.9 g,82.3 mmol) was added in one portion to a solution of C34 (35.0 g, 74.7mmol) in dichloromethane (750 mL), and the reaction mixture was stirredat room temperature (20° C.) for 2 hours. Dichloromethane (600 mL) andsaturated aqueous sodium bicarbonate solution (600 mL) were then added,and the resulting mixture was stirred for 10 minutes. The aqueous layerwas extracted with dichloromethane (2×300 mL), and the combined organiclayers were washed with saturated aqueous sodium thiosulfate solution(400 mL), dried over sodium sulfate, filtered, and concentrated underreduced pressure to provide the product (46.9 g) as a light brown foam.This material was impure by ¹H NMR, and was taken to the following stepwithout additional purification. ¹H NMR (400 MHz, CDCl₃), product peaksonly: δ 9.70 (s, 1H), 8.03-7.96 (m, 2H), 7.58 (br dd, J=7.4, 7.3 Hz,1H), 7.49 (br dd, J=7.8, 7.3 Hz, 2H), 7.26 (s, 1H), 4.16-4.06 (m, 2H),4.02 (d, half of AB quartet, J=11.5 Hz, 1H), 3.20-3.09 (m, 2H),2.71-2.63 (m, 1H), 2.07-1.91 (m, 2H).

Step 6. Synthesis ofN-[(4aR,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6,6-bis(hydroxymethyl)-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P10)

A solution of C35 (from the previous step; 46.9 g, 74.7 mmol) in1,4-dioxane (235 mL) and water (165 mL) was cooled to 0° C. Formaldehyde(37% solution in water; 44 mL, 590 mmol) was added, followed by additionof aqueous sodium hydroxide solution (1 M, 327 mL, 327 mmol), andstirring was continued at 0° C. for 1 hour. The reaction mixture wasthen allowed to warm to room temperature (18° C.), and was stirred at18° C. for 15 hours, whereupon it was acidified to a pH of approximately4 via addition of 1 M aqueous hydrochloric acid. The resulting mixturewas partitioned between saturated aqueous sodium chloride solution (400mL) and dichloromethane (400 mL), and the aqueous layer was extractedwith dichloromethane (2×200 mL). The combined organic layers were washedwith saturated aqueous sodium chloride solution (2×150 mL), dried oversodium sulfate, filtered, and concentrated in vacuo. Silica gelchromatography (Gradient, 0% to 4% methanol in dichloromethane) providedthe product as a pale yellow solid. Yield: 23.2 g, 46.5 mmol, 62% over 2steps. LCMS m/z 521.7 (bromine isotope pattern observed) [M+Na⁺]. ¹H NMR(400 MHz, CDCl₃) δ 8.04 (d, J=7.5 Hz, 2H), 7.56 (br dd, J=7.4, 7.3 Hz,1H), 7.47 (br dd, J=7.8, 7.3 Hz, 2H), 7.22 (s, 1H), 4.20 (d, J=11.8 Hz,1H), 4.11 (d, J=12.0 Hz, 1H), 3.81 (d, J=11.8 Hz, 1H), 3.77 (d, J=12.0Hz, 1H), 3.65 (AB quartet, J_(AB)=11.5 Hz, Δν_(AB)=59.4 Hz, 2H),3.20-3.08 (m, 2H), 2.60-2.53 (m, 1H), 2.02 (dd, J=13.9, 13.2 Hz, 1H),1.58-1.50 (m, 1H).

Preparation P11N-[(4aR,8a′R)-8a′-{4-[(2,4-Dimethoxybenzyl)amino]-1,3-thiazol-2-yl}-4a′,5′,8′,8a′tetrahydro-4′H-spiro[oxetane-3,6′-pyrano[3,4-d][1,3]thiazin]-2′-yl]benzamide(P11)

Step 1. Synthesis ofN-[(4aR,6S,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-({[tert-butyl(dimethyl)silyl]oxy}methyl)-6-(hydroxymethyl)-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(C36)

A solution of P10 (2.00 g, 4.01 mmol) and 1H-imidazole (0.546 g, 8.03mmol) in dichloromethane (40 mL) was cooled to 0° C., and a solution oftert-butyl(dimethyl)silyl chloride (1.21 g, 8.03 mmol) indichloromethane (20 mL) was added in a drop-wise manner. The reactionmixture was stirred at 0° C. for 1 hour and then, without removing theice bath, it was allowed to slowly warm up for an additional hour. Thereaction mixture was then partitioned between dichloromethane (100 mL)and water (100 mL); the aqueous layer was extracted with dichloromethane(2×50 mL) and the combined organic layers were washed with saturatedaqueous sodium chloride solution (200 mL), dried over sodium sulfate,filtered, and concentrated in vacuo. Silica gel chromatography(Gradient: 0% to 70% ethyl acetate in heptane) provided the product as awhite solid. The indicated regiochemistry of silylation was establishedvia NOE study of C40, which was synthesized from C36 (see PreparationP12 below). Yield: 1.42 g, 2.30 mmol, 57%. LCMS m/z 614.4 (bromineisotope pattern observed) [M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ 8.06 (br s,2H), 7.53-7.59 (m, 1H), 7.44-7.51 (m, 2H), 7.22 (s, 1H), 4.10-4.18 (m,2H), 3.80-3.87 (m, 1H), 3.72-3.79 (m, 2H), 3.50-3.54 (m, 1H), 3.14-3.22(m, 2H), 2.57-2.64 (m, 1H), 2.39-2.45 (m, 1H), 1.89-1.99 (m, 1H),1.64-1.72 (m, 1H), 0.85-0.90 (m, 9H), 0.07 (d, J=2.9 Hz, 6H).

Step 2. Synthesis of[(4aR,6R,8aR)-2-(benzoylamino)-8a-(4-bromo-1,3-thiazol-2-yl)-6-({[tert-butyl(dimethyl)silyl]oxy}methyl)-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-6-yl]methylmethanesulfonate (C37)

A solution of C36 (94.3 mg, 0.154 mmol) was dissolved in pyridine (1.9mL) and sequentially treated with 4-(dimethylamino)pyridine (5.41 mg,44.3 μmol) and p-toluenesulfonyl chloride (127 mg, 0.664 mmol). After 30minutes, more p-toluenesulfonyl chloride (127 mg, 0.664 mmol) was added,and stirring was continued at room temperature for 16 hours. Thereaction mixture was then partitioned between aqueous sodium bisulfatesolution (1 M, 150 mL) and dichloromethane (50 mL); the aqueous layerwas extracted with dichloromethane (2×50 mL), and the combined organiclayers were washed with aqueous sodium chloride solution, dried oversodium sulfate, filtered, and concentrated in vacuo. Silica gelchromatography (Gradient: 0% to 70% ethyl acetate in heptane) providedthe product. Yield: 109 mg, 0.141 mmol, 92%. ¹H NMR (400 MHz, CDCl₃) δ8.02 (br s, 2H), 7.87 (d, J=8.2 Hz, 2H), 7.54 (m, J=7.0 Hz, 1H),7.42-7.51 (m, 2H), 7.39 (d, J=7.8 Hz, 2H), 7.21 (s, 1H), 4.44 (d, J=10.5Hz, 1H), 4.22 (d, J=10.5 Hz, 1H), 3.66-3.75 (m, 1H), 3.55-3.65 (m, 2H),3.39 (d, J=10.1 Hz, 1H), 3.03-3.12 (m, 1H), 2.84-2.97 (m, 1H), 2.51 (d,J=12.8 Hz, 1H), 2.42 (s, 3H), 1.88-2.01 (m, 1H), 1.60-1.66 (m, 1H), 0.81(s, 9H), 0.00 (s, 6H).

Step 3. Synthesis ofN-[(4aR,8a′R)-8a′-(4-bromo-1,3-thiazol-2-yl)-4a′,5′,8′,8a′tetrahydro-4′H-spiro[oxetane-3,6′-pyrano[3,4-d][1,3]thiazin]-2′-yl]benzamide(C38)

A mixture of C37 (165.0 mg, 0.205 mmol) and tetrabutylammonium fluoride(1.0 M solution in tetrahydrofuran; 2.05 mL, 2.05 mmol) was heated at50° C. for 4 hours, then at 70° C. for 3 days. The reaction mixture waspartitioned between 5% aqueous sodium bicarbonate solution (50 mL) andethyl acetate (50 mL); the aqueous layer was extracted with ethylacetate (3×50 mL) and the combined organic layers were washed withsaturated aqueous sodium chloride solution, dried over sodium sulfate,filtered, and concentrated in vacuo. Silica gel chromatography(Gradient: 0% to 100% ethyl acetate in heptane) provided the product.LCMS m/z 482.3 (bromine isotope pattern observed) [M+H]⁺.

Step 4. Synthesis ofN-[(4aR,8a′R)-8a′-{4-[(2,4-dimethoxybenzyl)amino]-1,3-thiazol-2-yl}-4a′,5′,8′,8a′-tetrahydro-4′H-spiro[oxetane-3,6′-pyrano[3,4-d][1,3]thiazin]-2′-yl]benzamide(P11)

A flask charged with tris(dibenzylideneacetone)dipalladium(0) (11.4 mg,12.5 μmol),di-tert-butyl[2′,4′,6′-tri(propan-2-yl)biphenyl-2-yl]phosphane (16.4 mg,38.7 μmol), and sodium tert-butoxide (60.0 mg, 0.624 mmol) was purgedthree times with nitrogen, subsequently evacuating with vacuum aftereach purge. 1,4-Dioxane (0.7 mL) was added, and the flask was purgedthree times with nitrogen, subsequently evacuating with vacuum aftereach purge. The reaction mixture was heated to 95° C. for 5 minutes,whereupon a solution of C38 (120 mg, 0.250 mmol) and1-(2,4-dimethoxyphenyl)methanamine (63.8 μL, 0.425 mmol) in 1,4-dioxanewas added, and heating was continued at 95° C. for 15 minutes. Thereaction mixture was then cooled to room temperature using a water bath.Diatomaceous earth and water were added, and the resulting mixture wasfiltered through a pad of diatomaceous earth, washing withdichloromethane. The organic layer of the filtrate was washed threetimes with water (until the aqueous wash exhibited a neutral pH), twicewith 5% aqueous citric acid solution, twice with saturated aqueoussodium bicarbonate solution, and once with saturated aqueous sodiumchloride solution. It was then dried over sodium sulfate, filtered, andconcentrated in vacuo. Silica gel chromatography [Gradient: 10% to 100%(5% triethylamine in ethyl acetate) in heptane] provided the product.Yield: 25 mg, 44.1 μmol, 18%. LCMS m/z 567.5 [M+H⁺].

Preparation P12N-[(4aR,6R,8aR)-8a-(4-Bromo-1,3-thiazol-2-yl)-6-(methoxymethyl)-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P12)

Step 1. Synthesis ofN-[(4aR,6R,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-({[tert-butyl(dimethyl)silyl]oxy}methyl)-6-(iodomethyl)-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(C39)

To a solution of C36 (216 mg, 0.35 mmol) in tetrahydrofuran (12 mL) wereadded imidazole (96 mg, 1.4 mmol), triphenylphosphine (370, 1.4 mmol),and iodine (179 mg, 0.71 mmol). The reaction mixture was heated atreflux for 2.5 hours, whereupon it was allowed to cool to near roomtemperature. The reaction mixture was then partitioned between saturatedaqueous sodium thiosulfate solution (30 mL) and diethyl ether (2×30 mL);the combined organic layers were dried over sodium sulfate, filtered,and concentrated in vacuo. Silica gel chromatography (Gradient: 0% to75% ethyl acetate in heptane) provided the product as a white solid.Yield: 188.3 mg, 0.26 mmol, 74%. LCMS m/z 724.3 [M+H]⁺. ¹H NMR (400 MHz,CDCl₃) δ 7.95 (br m, 2H), 7.44-7.49 (m, 1H), 7.35-7.42 (m, 2H), 7.14 (s,1H), 3.89 (d, J=12.4 Hz, 1H), 3.75 (d, J=10.5 Hz, 1H), 3.59-3.69 (m,2H), 3.55 (d, J=10.9 Hz, 1H), 3.34 (d, J=9.7 Hz, 1H), 3.05-3.12 (m, 2H),2.52 (d, J=11.7 Hz, 1H), 2.11 (t, J=13.5 Hz, 1H), 1.83 (dd, J=14.2, 4.1Hz, 1H), 0.80 (s, 9H), −0.01 (d, J=9.4 Hz, 5H).

Step 2. Synthesis ofN-[(4aR,6R,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-({[tert-butyl(dimethyl)silyl]oxy}methyl)-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(C40)

A solution of lithium triethylborohydride in tetrahydrofuran (1.0 M, 2.5mL, 2.5 mmol) was added drop-wise to a 0° C. solution of C39 (180.5 mg,0.25 mmol) in tetrahydrofuran (12 mL). The ice bath was removed at thecompletion of the addition, and the reaction mixture was allowed to warmto room temperature over 20 minutes. It was then heated at reflux for 1hour, whereupon it was allowed to cool to room temperature. Aftercareful addition of saturated aqueous sodium bicarbonate solution (25mL), the mixture was extracted with diethyl ether (3×25 mL). Thecombined diethyl ether layers were dried over sodium sulfate, filtered,and concentrated in vacuo; silica gel chromatography (Gradient: 0% to40% ethyl acetate in heptane) afforded the product as a colorless solid.NOE studies on this compound confirmed the indicated relativestereochemistry: irradiation of the quaternary methyl group provided anenhancement of the signal for the methine proton at the ring fusion.Yield: 117.1 mg, 0.20 mmol, 79%. LCMS m/z 598.3 [M+H]⁺. ¹H NMR (400 MHz,CDCl₃) δ 7.89-8.23 (br m, 2H), 7.35-7.58 (m, 3H), 7.19 (s, 1H), 4.14 (d,J=11.3 Hz, 1H), 3.69 (d, J=12.1 Hz, 1H), 3.39-3.52 (m, 2H), 3.13-3.21(m, 2H), 2.56 (d, J=12.1 Hz, 1H), 1.91-2.16 (m, 1H), 1.48 (dd, J=14.1,3.9 Hz, 1H), 1.37 (s, 3H), 0.82 (s, 9H), −0.05-0.07 (m, 6H).

Step 3. Synthesis ofN-[(4aR,6R,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-(hydroxymethyl)-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(C41)

A solution of tetrabutylammonium fluoride in tetrahydrofuran (1.0 M,1.73 mL, 1.73 mmol) was added to a solution of C40 (344 mg, 0.58 mmol)in tetrahydrofuran (10 mL). The reaction mixture was stirred at roomtemperature for 16 hours, whereupon it was concentrated in vacuo.Purification via silica gel chromatography (Gradient: 0% to 100% ethylacetate in heptane) provided the product as a white solid. Yield: 286mg, 0.58 mmol, 100%. LCMS m/z 484.3 [M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ8.00-8.12 (br m, 2H), 7.51-7.59 (m, 1H), 7.42-7.49 (m, 2H), 7.23 (s,1H), 4.15 (d, J=12.1 Hz, 1H), 3.75 (d, J=12.1 Hz, 1H), 3.41-3.56 (m,2H), 3.27 (d, J=11.7 Hz, 1H), 3.18 (dd, J=13.0, 4.0 Hz, 1H), 2.59 (dd,J=12.8, 1.7 Hz, 1H), 2.19-2.35 (m, 1H), 1.41 (s, 3H), 1.35 (dd, J=13.7,4.5 Hz, 1H).

Step 4. Synthesis ofN-[(4aR,6R,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-(methoxymethyl)-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P12)

A solution of C41 (34.8 mg, 72 μmol) in tetrahydrofuran (1 mL) was addeddrop-wise to a suspension of sodium hydride (60% dispersion in mineraloil; 8.7 mg, 0.22 mmol) in tetrahydrofuran (0.5 mL) at 0° C. The icebath was removed and the reaction mixture was stirred at roomtemperature for 30 minutes, whereupon it was cooled to 0° C. Iodomethane(6.7 μL, 0.11 mmol) was added, and the ice bath was removed; thereaction mixture was stirred at room temperature for 2 hours, at whichtime more iodomethane (6.7 μL, 0.11 mmol) was added. After an additional2.5 hours, the reaction mixture was diluted with saturated aqueousammonium chloride solution (15 mL) and extracted with diethyl ether(3×15 mL). The combined organic layers were dried over sodium sulfate,filtered, and concentrated in vacuo. Silica gel chromatography(Gradient: 0% to 70% ethyl acetate in heptane) afforded the product as awhite solid. Yield: 25.6 mg, 52 μmol, 72%. LCMS m/z 498.3 [M+H]⁺. ¹H NMR(400 MHz, CDCl₃) δ 7.91 (d, J=7.4 Hz, 2H), 7.35-7.41 (m, 1H), 7.27-7.34(m, 2H), 7.06 (s, 1H), 3.99 (d, J=12.1 Hz, 1H), 3.59 (d, J=12.5 Hz, 1H),3.21 (s, 3H), 3.10-3.20 (m, 2H), 3.06-3.09 (m, 1H), 3.02 (dd, J=12.9,4.3 Hz, 1H), 2.42 (dd, J=13.1, 2.5 Hz, 1H), 1.89 (t, J=13.5 Hz, 1H),1.34 (d, J=4.3 Hz, 1H), 1.31 (s, 3H)

Preparation P13N-[(4aR,6S,8aR)-8a-(4-Bromo-1,3-thiazol-2-yl)-6-(fluoromethyl)-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P13)

Step 1. Synthesis ofN-[(4aR,6R,8aR)-6-[(benzyloxy)methyl]-8a-(4-bromo-1,3-thiazol-2-yl)-6-(hydroxymethyl)-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(C42)

Sodium hydride (60% in mineral oil; 98 mg, 2.4 mmol) was added to asolution of P10 (0.611 g, 1.23 mmol) in tetrahydrofuran (17.5 mL); thereaction mixture was stirred at room temperature for 10 minutes, andthen it was cooled to 0° C. Benzyl bromide (0.238 mL, 1.96 mmol) wasadded in a drop-wise manner, the ice bath was removed, and the reactionmixture was stirred at room temperature until complete consumption ofstarting material was observed by LCMS analysis. The reaction mixturewas partitioned between saturated aqueous ammonium chloride solution (20mL) and ethyl acetate (20 mL); the organic layer was washed withsaturated aqueous sodium chloride solution, dried over sodium sulfate,filtered, and concentrated in vacuo. Silica gel chromatography(Gradient: 20% to 100% ethyl acetate in heptane) provided the product asa white solid. Yield: 0.207 g, 0.352 mmol, 29%. LCMS m/z 590.4 (bromineisotope pattern observed) [M+H]⁺. ¹H NMR (400 MHz, CDCl₃),characteristic product peaks: δ: 8.07 (d, J=6.6 Hz, 2H), 7.53-7.58 (m,1H), 7.37-7.50 (m, 6H), 7.31-7.36 (m, 1H), 7.23 (s, 1H), 4.62 (s, 2H),4.15-4.23 (m, 1H), 3.88 (d, J=9.8 Hz, 1H), 3.73-3.81 (m, 2H), 3.68 (d,J=11.3 Hz, 1H), 3.52 (d, J=11.3 Hz, 1H), 3.20 (d, J=12.9 Hz, 1H), 3.12(dd, J=12.9, 4.3 Hz, 1H), 2.57 (dd, J=13.3, 2.3 Hz, 1H), 2.06-2.15 (m,1H), 1.73 (dd, J=14.0, 4.3 Hz, 1H).

Step 2. Synthesis ofN-[(4aR,6S,8aR)-6-[(benzyloxy)methyl]-8a-(4-bromo-1,3-thiazol-2-yl)-6-(iodomethyl)-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(C43)

Triethylamine (0.146 mL, 1.05 mmol) was added to a solution of C42 (154mg, 0.262 mmol) in acetonitrile (4.5 mL), and the solution was cooled to0° C. 1,1,2,2,3,3,4,4,4-Nonafluorobutane-1-sulfonyl fluoride (0.214 mL,1.22 mmol) was added in a drop-wise manner, and the reaction mixture wasallowed to warm room temperature. After 2.2 hours, potassium iodide(0.434 g, 2.61 mmol) was added and the reaction mixture was heated to45° C. for 16 hours. Additional potassium iodide (100 mg, 0.60 mmol) wasadded to the reaction mixture and heating was continued at 52° C. for 2hours. The reaction mixture was cooled to room temperature, concentratedunder reduced pressure, and partitioned between water (25 mL) anddiethyl ether (30 mL). The aqueous layer was extracted with diethylether (30 mL), and the combined organic layers were washed withsaturated aqueous sodium thiosulfate solution (10 mL), dried over sodiumsulfate, filtered, and concentrated in vacuo. Silica gel chromatography(Gradient: 0% to 60% ethyl acetate in heptane) provided the product as awhite solid. Yield: 0.126 g, 0.180 mmol, 69%. LCMS m/z 700.2 (bromineisotope pattern observed) [M+H]⁺. ¹H NMR (400 MHz, CDCl₃),characteristic product peaks: δ: 7.82-8.35 (m, 2H), 7.30-7.62 (m, 8H),7.25 (s, 1H), 4.65 (d, J=3.1 Hz, 2H), 4.03-4.20 (m, 1H), 3.97 (d, J=9.8Hz, 1H), 3.74-3.87 (m, 2H), 3.35-3.51 (m, 2H), 3.04-3.21 (m, 2H),2.52-2.61 (m, 1H), 2.01-2.13 (m, 1H), 1.87-1.99 (m, 1H).

Step 3. Synthesis ofN-[(4aR,6S,8aR)-6-[(benzyloxy)methyl]-8a-(4-bromo-1,3-thiazol-2-yl)-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(C44)

To a 0° C. solution of C43 (0.124 g, 0.178 mmol) in tetrahydrofuran (7.5mL) was added lithium triethylborohydride (1 M in tetrahydrofuran, 1.95mL, 1.95 mmol). The reaction mixture was allowed to warm to roomtemperature over 10 minutes, and was then heated at reflux for 5 hours.After cooling to room temperature, it was treated with methanol (15 mL),heated at reflux for 1 hour, and concentrated in vacuo. Silica gelcolumn chromatography (Gradient: 0% to 100% ethyl acetate in heptane)provided the product as a white solid. NOE studies supported thequaternary methyl group being on the alpha face of the molecule:irradiation of that methyl group provided no enhancement of the signalfor the methine proton at the ring fusion. Yield: 28 mg, 49 μmol, 28%.LCMS m/z 574.4 (bromine isotope pattern observed) [M+H]⁺. ¹H NMR (400MHz, CDCl₃), characteristic product peaks: δ 7.97-8.22 (m, 2H),7.53-7.62 (m, 1H), 7.49 (d, J=7.0 Hz, 2H), 7.42 (d, J=4.7 Hz, 4H),7.30-7.37 (m, 1H), 7.24 (s, 1H), 4.64 (s, 2H), 4.17-4.29 (m, 1H),3.65-3.81 (m, 3H), 3.17-3.29 (m, 1H), 3.13 (d, J=12.9 Hz, 1H), 2.56 (brs, 1H), 1.89-2.01 (m, 1H), 1.74-1.85 (m, 1H), 1.32 (s, 3H).

Step 4. Synthesis ofN-[(4aR,6S,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-(hydroxymethyl)-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(C45)

To a solution of C44 (52 mg, 91 μmol) in 1,2-dichloroethane (4 mL, 0.02M) was added methoxybenzene (30 μL, 0.27 mmol), and the reaction mixturewas heated to 60° C., followed by addition of trifluoromethanesulfonicacid (24 μL, 0.27 mmol). Heating was continued at 60° C. for 1.5 hours,whereupon the reaction mixture was cooled to room temperature andpartitioned between dichloromethane (20 mL) and saturated aqueous sodiumbicarbonate solution (15 mL). The aqueous layer was extracted withdichloromethane (2×20 mL), and the combined organic layers were driedover sodium sulfate, filtered, and concentrated in vacuo. Silica gelchromatography (Gradient: 0% to 100% ethyl acetate in heptane) providedthe product as a white solid. Yield: 32 mg, 66 μmol, 73%. LCMS m/z 484.3(bromine isotope pattern observed) [M+H]⁺. ¹H NMR (400 MHz, CDCl₃),characteristic product peaks: δ: 7.99-8.16 (m, 2H), 7.57 (d, J=7.8 Hz,1H), 7.46-7.54 (m, 2H), 7.24 (s, 1H), 4.24 (d, J=11.3 Hz, 1H), 4.08-4.14(m, 1H), 3.77 (d, J=12.1 Hz, 1H), 3.53 (d, J=10.5 Hz, 1H), 3.12-3.25 (m,2H), 2.59 (d, J=11.3 Hz, 1H), 2.03-2.13 (m, 1H), 1.69-1.77 (br m, 1H),1.60-1.69 (m, 1H), 1.33 (s, 3H).

Step 5. Synthesis ofN-[(4aR,6S,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-(fluoromethyl)-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P13)

To a solution of C45 (79 mg, 0.16 mmol) in acetonitrile (4 mL) was addedtriethylamine (91 μL, 0.66 mmol), followed by addition of1,1,2,2,3,3,4,4,4-nonafluorobutane-1-sulfonyl fluoride (0.101 mL, 0.57mmol) in a drop-wise manner, and the reaction mixture was stirred atroom temperature for 1 hour. Additional1,1,2,2,3,3,4,4,4-nonafluorobutane-1-sulfonyl fluoride (50 μL, 0.28mmol) was added, and the reaction mixture was stirred at roomtemperature for 1 hour. Potassium fluoride (0.143 g, 2.46 mmol) andKryptofix® 222(4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane; 0.566 g,1.47 mmol) were then added to the reaction mixture, which wasimmediately concentrated in vacuo and re-dissolved in tetrahydrofuran (5mL). The reaction mixture was stirred at room temperature for 30minutes, and heated to 30° C. for 65 minutes, whereupon it was dilutedwith saturated aqueous sodium bicarbonate solution (5 mL) and water (5mL). The aqueous layer was extracted with diethyl ether (3×15 mL), andthe combined organic layers were dried over sodium sulfate, filtered,and concentrated under reduced pressure. Silica gel chromatography(Gradient: 0% to 70% ethyl acetate in heptane) provided the product as awhite solid. Yield: 42 mg, 87 μmol, 54%. LCMS m/z 486.2 (bromine isotopepattern observed) [M+H]⁺. ¹H NMR (400 MHz, CDCl₃), characteristicproduct peaks: δ: 7.79-8.17 (m, 2H), 7.46-7.54 (m, 1H), 7.41 (br s, 2H),7.15 (s, 1H), 4.47-4.68 (m, 2H), 4.08-4.25 (m, 1H), 3.71 (d, J=12.1 Hz,1H), 3.02-3.25 (m, 2H), 2.47-2.58 (m, 1H), 1.91-2.06 (m, 1H), 1.65-1.75(m, 1H), 1.24 (s, 3H).

Preparation P14 Di-tert-butyl[(4aR,6R,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-(fluoromethyl)-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]imidodicarbonate(P14)

Step 1. Synthesis of(4aR,6R,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-({[tert-butyl(dimethyl)silyl]oxy}methyl)-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-amine(C46)

A mixture of C40 (1.209 g, 2.026 mmol), ethanol (10 mL) and methylaminesolution (33% by weight in ethanol; 10 mL) was stirred at roomtemperature for 6 hours, whereupon it was concentrated in vacuo.Purification via silica gel chromatography (Gradient: 0% to 100% ethylacetate in heptane) afforded the product as a white solid. Yield: 895mg, 1.82 mmol, 90%. LCMS m/z 494.3 (bromine isotope pattern observed)[M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ 7.17 (s, 1H), 4.57 (br s, 2H), 4.08(d, J=11.3 Hz, 1H), 3.68 (d, J=11.3 Hz, 1H), 3.49 (s, 2H), 3.17-3.23 (m,1H), 2.98-3.06 (m, 1H), 2.59 (dd, J=12.5, 2.7 Hz, 1H), 1.93 (t, J=13.5Hz, 1H), 1.40-1.45 (m, 1H), 1.40 (s, 3H), 0.91 (s, 9H), 0.07 (s, 6H).

Step 2. Synthesis of di-tert-butyl[(4aR,6R,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-({[tert-butyl(dimethyl)silyl]oxy}methyl)-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]imidodicarbonate(C47)

To a mixture of C46 (890 mg, 1.81 mmol) in tetrahydrofuran (40 mL) wasadded di-tert-butyl-dicarbonate (2.17 g, 9.94 mmol) followed by4-(dimethylamino)pyridine (662 mg, 5.42 mmol). The reaction mixture wasstirred at room temperature for 3 hours, whereupon it was concentratedin vacuo. Silica gel chromatography (Gradient: 0% to 80% ethyl acetatein heptane) provided the product as a white solid. Yield: 1.188 g, 1.71mmol, 95%. ¹H NMR (400 MHz, CDCl₃) δ 7.21 (s, 1H), 4.04 (d, J=11.7 Hz,1H), 3.85 (d, J=11.7 Hz, 1H), 3.51 (s, 2H), 3.34 (dd, J=12.9, 3.9 Hz,1H), 3.15-3.22 (m, 1H), 2.66 (dd, J=12.9, 2.7 Hz, 1H), 1.99 (t, J=13.5Hz, 1H), 1.53 (s, 18H), 1.47-1.52 (m, 1H), 1.42 (s, 3H), 0.91 (s, 9H),0.07 (s, 6H).

Step 3. Synthesis of di-tert-butyl[(4aR,6R,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-(hydroxymethyl)-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]imidodicarbonate(C48)

To a mixture of C47 (1.18 g, 1.70 mmol) in tetrahydrofuran was addedtetrabutylammonium fluoride solution (1 M in tetrahydrofuran; 4.26 mL,4.26 mmol). The reaction mixture was stirred at room temperature for 4hours, concentrated in vacuo, and subjected to two purifications viasilica gel chromatography (Gradient: 0% to 100% ethyl acetate inheptane); the product was isolated as a white solid. Yield: 694 mg, 1.20mmol, 70%. LCMS m/z 580.2 (bromine isotope pattern observed) [M+H]⁺. ¹HNMR (400 MHz, CDCl₃) δ 7.22 (s, 1H), 4.08 (d, J=11.3 Hz, 1H), 3.89 (d,J=11.3 Hz, 1H), 3.43-3.61 (m, 2H), 3.33 (dd, J=12.9, 3.9 Hz, 1H),3.21-3.28 (m, 1H), 2.66 (dd, J=12.9, 2.7 Hz, 1H), 2.45 (t, J=13.5 Hz,1H), 2.39 (dd, J=8.0, 4.5 Hz, 1H), 1.54 (s, 18H), 1.38 (s, 3H)

Step 4. Synthesis of di-tert-butyl[(4aR,6R,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-(fluoromethyl)-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]imidodicarbonate(P14)

To a mixture of C48 (66 mg, 0.11 mmol) in acetonitrile (3 mL) was addedtriethylamine (64 μL, 0.46 mmol), followed by drop-wise addition of1,1,2,2,3,3,4,4,4-nonafluorobutane-1-sulfonyl fluoride (70 μL, 0.40mmol). The reaction mixture was stirred at room temperature for 50minutes, during which time a white precipitate formed. After anadditional 90 minutes, the mixture was concentrated to a white solid.This solid was dissolved in tetrahydrofuran (4 mL) and treated withpotassium fluoride (99.4 mg, 1.71 mmol), followed by Kryptofix® 222 (438mg, 1.14 mmol). The reaction mixture was stirred at 55° C. for 3 hours,then at 65° C. for another 1 hour and 45 minutes. It was then allowed tocool to room temperature, whereupon saturated aqueous sodium bicarbonatesolution (10 mL) and water (5 mL) were added. The resulting mixture wasextracted with diethyl ether (3×20 mL), and the combined organic layerswere dried over sodium sulfate, filtered, and concentrated in vacuo.Silica gel chromatography (Gradient: 0% to 55% ethyl acetate in heptane)afforded the product as a white solid. Yield: 55.2 mg, 95 μmol, 83%.LCMS m/z 582.3 (bromine isotope pattern observed) [M+H]⁺. ¹H NMR (400MHz, CDCl₃) δ 7.22 (s, 1H), 4.16-4.39 (m, 2H), 3.87-4.08 (m, 2H), 3.34(dd, J=12.9, 3.9 Hz, 1H), 3.20-3.28 (m, 1H), 2.65 (dd, J=12.9, 2.7 Hz,1H), 2.10 (t, J=13.3 Hz, 1H), 1.53 (s, 18H), 1.51 (d, J=1.6 Hz, 3H),1.42 (dd, J=13.3, 4.3 Hz, 1H).

Preparation P15 di-tert-Butyl[(4aR,8aR)-8a-(4-amino-1,3-thiazol-2-yl)-6,6-bis(fluoromethyl)-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]imidodicarbonate(P15)

Step 1. Synthesis ofN-[(4aR,8a′R)-8a′-(4-bromo-1,3-thiazol-2-yl)-2-(4-methoxyphenyl)-4a′,5′,8′,8a′-tetrahydro-4′H-spiro[1,3-dioxane-5,6′-pyrano[3,4-d][1,3]thiazin]-2′-yl]benzamide(C49)

4-Methoxybenzaldehyde (0.29 mL, 2.39 mmol), P10 (0.298 g, 0.598 mmol),sodium sulfate (1.0 g), and benzenesulfonic acid (9.46 mg, 59.8 μmol)were combined in toluene (30 mL), and heated to reflux. After 20 hours,the reaction mixture was cooled to ambient temperature and partitionedbetween saturated aqueous sodium bicarbonate solution (50 mL) and ethylacetate (50 mL). The aqueous layer was extracted with ethyl acetate(2×50 mL), and the combined organic layers were washed with saturatedaqueous sodium chloride solution, dried over sodium sulfate, filtered,and concentrated in vacuo. Chromatography on silica gel (Gradient: 0% to80% ethyl acetate in heptane) afforded two diastereomers, which wereseparated for characterization purposes, then recombined for thesubsequent reaction. Major diastereomer: Yield: 0.216 g, 0.350 mmol,59%. ¹H NMR (400 MHz, CDCl₃), characteristic peaks: δ 7.86-8.24 (m, 2H),7.56 (m, 1H), 7.45-7.52 (m, 2H), 7.38-7.44 (m, 2H), 7.24 (s, 1H),6.88-6.94 (m, 2H), 5.44 (s, 1H), 4.82 (dd, J=10.9, 2.3 Hz, 1H), 4.09 (d,J=12.5 Hz, 1H), 3.97 (dd, J=10.9, 2.3 Hz, 1H), 3.71-3.85 (m, 6H),3.14-3.30 (m, 2H), 2.69 (m, 1H), 2.54 (dd, J=14.0, 4.3 Hz, 1H), 2.01 (m,1H).

Minor diastereomer: Yield: 57 mg, 92 μmol, 15%. ¹H NMR (400 MHz, CDCl₃),characteristic peaks: δ 8.05 (m, 2H), 7.54-7.62 (m, 1H), 7.41-7.53 (m,4H), 7.24 (s, 1H), 6.85-6.92 (m, 2H), 5.50 (s, 1H), 4.97 (dd, J=12.9,2.7 Hz, 1H), 4.26 (d, J=12.5 Hz, 1H), 4.07 (dd, J=11.9, 2.9 Hz, 1H),3.93 (d, J=12.5 Hz, 1H), 3.73-3.87 (m, 5H), 3.04-3.26 (m, 2H), 2.57 (d,J=10.9 Hz, 1H), 1.89 (t, J=13.5 Hz, 1H), 1.42 (dd, J=13.9, 4.1 Hz, 1H).

Step 2. Synthesis of di-tert-butyl[(4a′R,8a′R)-8a′-(4-bromo-1,3-thiazol-2-yl)-2-(4-methoxyphenyl)-4a′,5′,8′,8a′-tetrahydro-4′H-spiro[1,3-dioxane-5,6′-pyrano[3,4-d][1,3]thiazin]-2′-yl]imidodicarbonate(C50)

To a mixture of C49 (0.273 g, 0.443 mmol) in ethanol (6.7 mL) anddichloromethane (8.7 mL) was added hydrazine monohydrate (0.235 mL, 3.10mmol), and the reaction mixture was stirred for 3 hours. Concentrationin vacuo provided a white solid, which was suspended in acetonitrile (8mL), and treated with 4-(dimethylamino)pyridine (10 mg) anddi-tert-butyl dicarbonate (0.30 g, 1.37 mmol). After 15 minutes, a finewhite solid precipitated out of solution; this was collected viafiltration to afford the product as an inseparable mixture (1.00:0.16)of diastereomers. Yield: 0.119 g, 0.167 mmol, 38%. LCMS m/z 714.3(bromine isotope pattern observed) [M+H]⁺. ¹H NMR (400 MHz, CDCl₃),characteristic peaks: δ 7.43 (m, 2.3H), 7.22 (s, 1H), 6.91 (m, 2.3H),5.51-5.48 (m, 0.16H), 5.43 (s, 1H), 4.76-4.83 (m, 1.2H), 4.08-4.03 (m,1.2H), 3.97 (m, 2.2H), 3.90 (d, 2.2H), 3.84-3.73 (m, 5.8H), 3.36-3.29(m, 1.2H), 3.27-3.18 (m, 1.2H), 2.79-2.70 (m, 1.2H), 2.48-2.38 (m,1.2H), 2.23-2.10 (m, 1.2H), 1.56 (s, 2.8H), 1.53 (s, 18H).

Step 3. Synthesis of di-tert-butyl[(4aR,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6,6-bis(hydroxymethyl)-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]imidodicarbonate(C51)

Ceric ammonium nitrate (0.445 g, 0.811 mmol) was added to a 0° C.solution of C50 (119 mg, 0.167 mmol) in acetonitrile (3.4 mL) and water(0.34 mL). The reaction mixture was allowed to warm to room temperatureand stirred for 30 minutes, whereupon it was diluted with ethyl acetate(50 mL) and treated with saturated aqueous sodium bicarbonate solution(40 mL), then with water (100 mL). The resulting mixture was extractedwith ethyl acetate (2×40 mL), and the combined organic layers were driedover sodium sulfate, filtered, and concentrated in vacuo. Chromatographyon silica gel (Gradient: 0% to 100% ethyl acetate in heptane) affordedthe product as a viscous oil. Yield: 73 mg, 0.123 mmol, 74%. ¹H NMR (400MHz, CDCl₃), characteristic peaks: δ 7.22 (s, 1H), 4.20 (dd, J=11.9, 3.7Hz, 1H), 4.07-4.01 (m, 1H), 3.92 (d, J=11.3 Hz, 1H), 3.76 (m, 2H), 3.61(dd, J=11.3, 6.6 Hz, 1H), 3.29 (dd, J=13.3, 3.9 Hz, 1H), 3.19 (dd,J=13.1, 2.9 Hz, 1H), 2.67 (m, 1H), 2.34 (m, 1H), 2.28 (t, J=13.9 Hz,1H), 2.17 (m, 1H), 1.54 (s, 18H), 1.47 (m, 1H).

Step 4. Synthesis of di-tert-butyl[(4aR,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6,6-bis(fluoromethyl)-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]imidodicarbonate(C52)

Triethylamine (0.169 mL, 1.21 mmol) and1,1,2,2,3,3,4,4,4-nonafluorobutane-1-sulfonyl fluoride (0.187 mL, 1.06mmol) were sequentially added to a 0° C. solution of C51 (90 mg, 0.15mmol) in tetrahydrofuran (5 mL). After 3 hours, LCMS showed formation ofan intermediate corresponding to the bis-sulfonate intermediate {m/z1159.8 (bromine isotope pattern observed) [M+H]⁺}. At this time,potassium fluoride (0.132 g, 2.27 mmol) and Kryptofix® 222 (0.582 g,1.51 mmol) were added to the reaction mixture, which was then stirred at55° C. for 1 hour. The reaction mixture was cooled, and diluted withaqueous sodium bicarbonate solution (50 mL) and ethyl acetate (50 mL).The aqueous layer was extracted with ethyl acetate (3×25 mL), and thecombined organic layers were washed with saturated aqueous sodiumchloride solution, dried over sodium sulfate, filtered, and concentratedunder reduced pressure. Silica gel chromatography (Gradient: 0% to 60%ethyl acetate in heptane) afforded the product as a yellow gum. Yield:35 mg, 58 μmol, 39%. LCMS m/z 600.2 (bromine isotope pattern observed)[M+H]⁺. ¹H NMR (400 MHz, CDCl₃), characteristic peaks: δ 7.23 (s, 1H),4.96-4.24 (m, 4H), 4.11-3.91 (m, 2H), 3.32 (dd, J=12.9, 3.9 Hz, 1H),3.26-3.17 (m, 1H), 2.74-2.66 (m, 1H), 2.24-2.06 (m, 1H), 1.76-1.65 (m,1H), 1.56-1.50 (m, 18H).

Step 5. Synthesis of di-tert-butyl[(4aR,8aR)-8a-(4-amino-1,3-thiazol-2-yl)-6,6-bis(fluoromethyl)-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]imidodicarbonate(P15)

A solution of C52 (35 mg, 58 μmol) andtrans-N,N′-dimethylcyclohexane-1,2-diamine (10 mg, 70 μmol) in ethanol(1 mL) was treated with sodium azide (36 mg, 0.56 mmol), and with asolution of sodium L-ascorbate (6 mg, 30 μmol) in water (0.15 mL). Thereaction mixture was briefly evacuated under high vacuum and thenrefilled with nitrogen (3 cycles). It was then stirred under nitrogen atambient temperature for 15 minutes, followed by the addition ofcopper(I) iodide (5 mg, 30 μmol). The resulting blue solution was heatedto 70° C. for 20 minutes, whereupon the reaction mixture was removedfrom the heat and partitioned between saturated aqueous sodiumbicarbonate solution (25 mL), water (25 mL), and ethyl acetate (25 mL).The aqueous layer was extracted with ethyl acetate (2×25 mL), and thecombined organic layers were dried over sodium sulfate, filtered, andconcentrated in vacuo. To this residue was added ethanol (2.0 mL), water(0.30 mL), ammonium chloride (10 mg, 0.187 mmol) and zinc dust (10 mg,0.15 mmol). The resulting suspension was heated to 60° C. for 25minutes, at which time it was cooled, and worked up as described above.Chromatography on silica gel (Gradient: 0% to 100% ethyl acetate inheptane) afforded the product as a white solid. Yield: 7 mg, 13 μmol,20%. LCMS m/z 535.4 [M+H]⁺.

Preparation P16 Di-tert-butyl[(4aR,6S,8aR)-8a-(4-amino-1,3-thiazol-2-yl)-6-ethyl-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]imidodicarbonate(P16)

Step 1. Synthesis of di-tert-butyl[(4aR,6R,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-formyl-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]imidodicarbonate(C53)

A solution of C48 (485 mg, 0.838 mmol) in dichloromethane (15 mL) wastreated with triethylamine (0.7 mL, 5 mmol) and dimethyl sulfoxide (0.71mL, 10 mmol), and cooled to 0° C. Pyridine-sulfur trioxide complex (820mg, 5.0 mmol) was then added and the reaction mixture was stirred atroom temperature for 18 hours, whereupon it was quenched with saturatedaqueous ammonium chloride solution (30 mL) and water (15 mL), anddiluted with dichloromethane (20 mL). The aqueous layer was extractedwith dichloromethane (2×40 mL), and the combined organics layers werewashed with saturated aqueous sodium chloride solution (30 mL), driedover sodium sulfate, filtered, and concentrated in vacuo. Silica gelchromatography (Gradient: 0% to 95% ethyl acetate in heptane) providedthe product as a white solid. Yield: 267 mg, 0.463 mmol, 55%. LCMS m/z578.2 (bromine isotope pattern observed) [M+H]⁺. ¹H NMR (400 MHz, CDCl₃)δ 9.62 (s, 1H), 7.25 (s, 1H), 4.10-4.18 (m, 1H), 4.00-4.07 (m, 1H), 3.35(dd, J=12.9, 3.9 Hz, 1H), 3.23-3.31 (m, 1H), 2.70 (dd, J=12.9, 2.7 Hz,1H), 2.16-2.26 (m, 1H), 1.49-1.55 (m, 21H), 1.48 (d, J=4.29 Hz, 1H)

Step 2. Synthesis of di-tert-butyl[(4aR,6R,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-formyl-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]imidodicarbonate(C54)

Potassium tert-butoxide (1.0 M solution in tetrahydrofuran; 0.77 mL,0.77 mmol) was added drop-wise to a suspension ofmethyltriphenylphosphomium bromide (338 mg, 0.926 mmol) intetrahydrofuran (10 mL), and the reaction mixture was stirred at roomtemperature for 15 minutes before being cooled to 0° C. A solution ofC53 (178 mg, 0.309 mmol) in tetrahydrofuran (2 mL) was added drop-wiseand stirring was continued at room temperature for 2 hours. The reactionwas then quenched via addition of saturated aqueous ammonium chloridesolution (10 mL) and water (5 mL), and the mixture was extracted withdiethyl ether (3×15 mL). The combined organic layers were dried oversodium sulfate, filtered, and concentrated in vacuo; silica gelchromatography (Gradient: 0% to 70% ethyl acetate in heptane) affordedthe product as a white solid. Yield: 141 mg, 0.245 mmol, 79%. LCMS m/z576.3 (bromine isotope pattern observed) [M+H]⁺. ¹H NMR (400 MHz, CDCl₃)δ 7.23 (s, 1H), 5.91-6.03 (m, 1H), 5.21-5.33 (m, 1H), 5.07 (dd, J=10.9,1.2 Hz, 1H), 4.10 (d, J=11.7 Hz, 1H), 3.94 (d, J=11.7 Hz, 1H), 3.36 (dd,J=12.9, 3.9 Hz, 1H), 3.22-3.31 (m, 1H), 2.68 (dd, J=12.9, 2.7 Hz, 1H),2.07-2.26 (m, 1H), 1.55-1.59 (m, 3H), 1.52 (s, 18H), 1.48-1.51 (m, 1H).

Step 3. Synthesis of di-tert-butyl[(4aR,6S,8aR)-8a-(4-amino-1,3-thiazol-2-yl)-6-ethyl-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]imidodicarbonate(P16)

Compound C54 (137 mg, 0.238 mmol) was dissolved in a mixture of ethanoland water (6:1, 3 mL, which had been sparged with argon);trans-N,N′-dimethylcyclohexane-1,2-diamine (41 mg, 0.28 mmol) was thenadded, followed by sodium azide (147 mg, 2.27 mmol) and sodiumL-ascorbate (24.1 mg, 0.119 mmol). The resulting mixture was purged invacuo and refilled with nitrogen (three cycles), then the reactionmixture was stirred at room temperature for 15 minutes. Copper(I) iodide(22.7 mg, 0.119 mmol) was added and the resulting blue solution washeated to 70° C. for 4 hours, whereupon it was cooled to roomtemperature, concentrated in vacuo, and treated with half-saturatedaqueous sodium bicarbonate solution (20 mL). The aqueous layer wasextracted with ethyl acetate (2×25 mL), and the combined organic layerswere dried over sodium sulfate, filtered, and concentrated under reducedpressure. The residue (130 mg) was dissolved in methanol (10 mL) andtreated with 10% palladium on carbon (50 mg). The reaction mixture waspressurized with 75 psi nitrogen and evacuated (three cycles), thenplaced under 50 psi hydrogen and evacuated (three cycles). It was thenstirred under 50 psi hydrogen for 7 hours. 10% Palladium on carbon (100mg) was added and the reaction mixture was stirred for 18 hours under 65psi hydrogen, whereupon it was filtered through diatomaceous earth, andthe filtrate was concentrated in vacuo. Silica gel chromatography(Gradient: 0% to 100% ethyl acetate in heptane) provided the product asa white solid. Yield: 43 mg, 84 μmol, 35%. LCMS m/z 513.4 [M+H]⁺. ¹H NMR(400 MHz, CDCl₃) δ 5.86 (s, 1H), 3.87-4.00 (m, 3H), 3.78 (d, J=11.7 Hz,1H), 3.32 (dd, J=12.9, 3.9 Hz, 1H), 2.98-3.09 (m, 1H), 2.52 (dd, J=12.7,2.5 Hz, 1H), 1.88-2.00 (m, 1H), 1.48-1.54 (m, 3H), 1.41-1.47 (m, 18H),1.25-1.31 (m, 3H), 0.86 (t, J=7.6 Hz, 3H).

Preparation P17 N-[cis-8a′-{4-[(2,4-Dimethoxybenzyl)amino]-1,3-thiazol-2-yl}-4a′,5′,8′,8a′-tetrahydro-4′H-spiro[cyclopropane-1,6′-pyrano[3,4-d][1,3]thiazin]-2′-yl]benzamide(P17)

Step 1. Synthesis of 1-(benzyloxy)-2-(phenoxymethyl)pent-4-en-2-ol (C55)

Pyridine-sulfur trioxide complex (51.3 g, 316 mmol) was added to a 0° C.solution of 1,3-bis(benzyloxy)propan-2-ol (20.0 g, 73.4 mmol),triethylamine (49.8 mL, 358 mmol), and dimethyl sulfoxide (25.0 mL, 352mmol) in dichloromethane (77 mL). The resulting solution was allowed towarm to room temperature and stir for 2 hours. The reaction mixture wasthen partitioned between ethyl acetate (250 mL) and water (500 mL); theorganic layer was washed sequentially with aqueous hydrochloric acid (2M, 2×250 mL), water (2×200 mL), and saturated aqueous sodium chloridesolution (500 mL). It was then dried over sodium sulfate, filtered, andconcentrated under reduced pressure to yield intermediate1,3-bis(benzyloxy)propan-2-one as an orange oil (20.8 g, 77.0 mmol).This material was dissolved in tetrahydrofuran (77 mL) and cooled to 0°C.; allylmagnesium chloride (2.0 M solution in tetrahydrofuran, 38.5 mL,77.0 mmol) was slowly added to this solution. The reaction mixture wasallowed to warm to room temperature and stir at room temperature for 16hours, whereupon it was quenched via slow addition of aqueoushydrochloric acid (1 M, 500 mL). The resulting biphasic solution wasextracted with diethyl ether (3×200 mL). The combined organic layerswere washed with water (2×150 mL), dried over magnesium sulfate,filtered, and concentrated under reduced pressure. Silica gelchromatography (Gradient: 0% to 80% ethyl acetate in heptane) affordedthe product as a colorless oil. Yield: 17.0 g, 54.4 mmol, 74%. LCMS m/z335.4 [M+Na⁺]. ¹H NMR (400 MHz, CDCl₃), characteristic product peaks: δ7.27-7.38 (m, 10H), 5.78-5.93 (m, 1H), 5.04-5.14 (m, 2H), 4.54 (s, 4H),3.39-3.52 (m, 4H), 2.36 (dt, J=7.4, 1.1 Hz, 2H).

Step 2. Synthesis of({2-[(benzyloxy)methyl]-2-(2,2-dimethoxyethoxy)pent-4-en-1-yl}oxy)benzene(C56)

To a suspension of sodium hydride (60% dispersion in mineral oil, 4.30g, 108 mmol) in 1,4-dioxane (68 mL) was added C55 (16.0 g, 51.2 mmol) ina drop-wise manner. After the addition was completed, the reactionmixture was stirred at room temperature for 45 minutes, whereupon2-bromo-1,1-dimethoxyethane (12.1 mL, 102 mmol) was slowly added. Thereaction mixture was heated to 100° C. for 4 days, and then cooled toroom temperature and poured into ice water (1 L). The aqueous layer wasextracted with ethyl acetate (3×250 mL), and the combined organic layerswere washed with saturated aqueous sodium chloride solution (500 mL),dried over sodium sulfate, filtered, and concentrated in vacuo. Silicagel chromatography (Gradient: 0% to 20% ethyl acetate in heptane)afforded the product as a yellow oil. Yield: 11.6 g, 29 mmol, 57%. LCMSm/z 423.5 [M+Na⁺]. ¹H NMR (400 MHz, CDCl₃), characteristic productpeaks: δ 7.26-7.35 (m, 10H), 5.75-5.90 (m, 1H), 5.03-5.12 (m, 2H), 4.51(s, 4H), 4.44 (t, J=5.2 Hz, 1H), 3.60 (d, J=5.3 Hz, 2H), 3.46-3.55 (m,4H), 3.36 (s, 6H), 2.35-2.40 (m, 2H).

Step 3. Synthesis of5,5-bis[(benzyloxy)methyl]-3,3a,4,5-tetrahydro-7H-pyrano[3,4-c][1,2]oxazole(C57)

Hydroxylamine hydrochloride (2.89 g, 41.6 mmol) was added to a solutionof C56 (11.6 g, 28.9 mmol) in ethanol (56 mL) and water (10 mL). Thereaction mixture was heated to 70° C. for 2.5 hours, whereupon it wascooled to room temperature. Sodium acetate (4.89 g, 57.8 mmol) and water(10 mL) were added, and the reaction mixture was allowed to stir at roomtemperature for 10 minutes. It was then concentrated under reducedpressure to remove ethanol, and the residue was partitioned betweendichloromethane (100 mL) and water (150 mL). The aqueous layer wasextracted with dichloromethane (2×150 mL), and the combined organiclayers were washed with saturated aqueous sodium chloride solution (300mL), dried over sodium sulfate, filtered, and concentrated in vacuo toprovide intermediate2-({1-(benzyloxy)-2-[(benzyloxy)methyl]pent-4-en-2-yl}oxy)-N-hydroxyethanimineas a colorless oil (12.5 g). This material was dissolved indichloromethane (160 mL), cooled to −10° C. (internal temperature,ice-methanol bath), and treated with aqueous sodium hypochloritesolution (5.65-6%, 44.9 mL, 37.5 mmol) in a drop-wise manner, such thatthe temperature of the reaction mixture did not exceed 0° C. throughoutthe addition. The reaction mixture was stirred at −10° C. for 3 hoursand then allowed to warm to room temperature and stir for 16 hours,whereupon it was diluted with water (500 mL) and the aqueous layer wasextracted with dichloromethane (2×250 mL). The combined organic layerswere washed with saturated aqueous sodium chloride solution (500 mL),dried over sodium sulfate, filtered, and concentrated in vacuo. Silicagel chromatography (Gradient: 0% to 80% ethyl acetate in heptane)afforded the product as a colorless oil. Yield: 8.91 g, 24.2 mmol, 71%.LCMS m/z 368.4 [M+H]⁺. ¹H NMR (400 MHz, CDCl₃), characteristic productpeaks: δ 7.27-7.39 (m, 10H), 4.52-4.63 (m, 6H), 4.44-4.50 (m, 1H),3.66-3.78 (m, 3H), 3.54-3.62 (m, 1H), 3.51 (d, J=9.8 Hz, 1H), 3.40 (d,J=9.6 Hz, 1H), 2.31 (dd, J=13.2, 6.7 Hz, 1H), 1.59 (dd, J=13.3, 11.9 Hz,1H).

Step 4. Synthesis ofcis-5,5-bis[(benzyloxy)methyl]-7a-(4-bromo-1,3-thiazol-2-yl)hexahydro-1H-pyrano[3,4-c][1,2]oxazole(C58)

Conversion of C57 to C58 was effected using the method described forsynthesis of C22 from C21 in Preparation P4. The product was isolated asa yellow oil. Yield: 9.80 g, 18.4 mmol, 76%. LCMS m/z 533.3 (bromineisotope pattern observed) [M+H]⁺. ¹H NMR (400 MHz, CDCl₃),characteristic product peaks: δ: 7.27-7.38 (m, 10H), 7.19 (s, 1H),4.51-4.62 (m, 4H), 4.08 (d, J=12.9 Hz, 1H), 3.77-3.86 (m, 2H), 3.67-3.77(m, 2H), 3.37-3.66 (m, 3H), 3.23-3.32 (m, 1H), 1.96 (dd, J=14.6, 6.7 Hz,1H), 1.68 (dd, J=14.5, 11.2 Hz, 1H)

Step 5. Synthesis of[cis-7a-(4-bromo-1,3-thiazol-2-yl)-5,5-bis(hydroxymethyl)hexahydro-1H-pyrano[3,4-c][1,2]oxazol-1-yl](phenyl)methanone(C59)

Benzoyl chloride (0.961 mL, 8.28 mmol) was added to a 0° C. solution ofC58 (2.20 g, 4.14 mmol) and triethylamine (1.15 mL, 8.28 mmol) intetrahydrofuran (41 mL). The reaction mixture was allowed to warm toroom temperature and stir for 16 hours, whereupon it was partitionedbetween ethyl acetate (150 mL) and water (150 mL). The organic layer waswashed sequentially with water (2×150 mL) and with saturated aqueoussodium chloride solution (300 mL), dried over sodium sulfate, filtered,and concentrated in vacuo. Silica gel chromatography (Gradient: 0% to50% ethyl acetate in heptane) afforded intermediate[cis-5,5-bis[(benzyloxy)methyl]-7a-(4-bromo-1,3-thiazol-2-yl)hexahydro-1H-pyrano[3,4-c][1,2]oxazol-1-yl](phenyl)methanoneas a light yellow oil (2.44 g, 3.84 mmol). This material was dissolvedin 1,2-dichloroethane (26 mL) and treated with methoxybenzene (2.08 mL,19.2 mmol), followed by trifluoromethanesulfonic acid (1.67 mL, 19.2mmol). The reaction mixture was stirred at room temperature for 15minutes, at which time aqueous sodium hydroxide solution (1 M, 100 mL)was added, followed by dichloromethane (100 mL). The resulting mixturewas stirred vigorously at room temperature for 10 minutes. The aqueouslayer was then extracted with dichloromethane (2×150 mL), and thecombined organic layers were dried over sodium sulfate, filtered, andconcentrated under reduced pressure. Silica gel chromatography(Gradient: 40% to 100% ethyl acetate in heptane) afforded the product asa white solid. Yield: 1.27 g, 2.79 mmol, 73%. LCMS m/z 457.2 (bromineisotope pattern observed) [M+H]⁺. ¹H NMR (400 MHz, CDCl₃),characteristic product peaks: δ 7.78-7.85 (m, 2H), 7.48-7.54 (m, 1H),7.39-7.47 (m, 2H), 7.22 (s, 1H), 4.81 (d, J=12.7 Hz, 1H), 4.44 (dd,J=8.1, 6.2 Hz, 1H), 4.28 (d, J=12.7 Hz, 1H), 3.64-3.90 (m, 5H),3.54-3.62 (m, 1H), 3.00 (dd, J=8.6, 4.3 Hz, 1H), 1.98-2.03 (m, 1H), 1.94(dd, J=8.2, 4.5 Hz, 1H), 1.83-1.92 (m, 1H).

Step 6. Synthesis of[cis-7a-(4-bromo-1,3-thiazol-2-yl)-5,5-bis(iodomethyl)hexahydro-1H-pyrano[3,4-c][1,2]oxazol-1-yl](phenyl)methanone(C60)

To a 0° C. solution of C59 (3.07 g, 6.74 mmol) in acetonitrile (135 mL),was added triethylamine (3.76 mL, 27.0 mmol), followed by drop-wiseaddition of 1,1,2,2,3,3,4,4,4-nonafluorobutane-1-sulfonyl fluoride (4.15mL, 23.6 mmol). Once the addition was completed, the reaction mixturewas allowed to warm to room temperature and stir for 3 hours. Potassiumiodide (11.2 g, 67.4 mmol) was then added, and the reaction mixture washeated to 45° C. for 16 hours, whereupon it was concentrated in vacuoand partitioned between diethyl ether (300 mL) and water (500 mL). Theaqueous layer was extracted with diethyl ether (2×150 mL), and thecombined organic layers were washed with saturated aqueous sodiumthiosulfate solution (200 mL) and with saturated aqueous sodium chloridesolution (300 mL), dried over sodium sulfate, filtered and concentratedin vacuo. Silica gel chromatography (Gradient: 0% to 70% ethyl acetatein heptane) afforded the product as a white solid. Yield: 3.88 g, 5.75mmol, 85%. LCMS m/z 677.0 (bromine isotope pattern observed) [M+H]⁺. ¹HNMR (400 MHz, CDCl₃), characteristic product peaks: δ: 7.78-7.83 (m,2H), 7.46-7.53 (m, 1H), 7.38-7.44 (m, 2H), 7.26 (s, 1H, assumed;partially obscured by solvent peak), 4.66 (d, J=13.3 Hz, 1H), 4.43-4.51(m, 2H), 3.93 (dd, J=8.2, 2.3 Hz, 1H), 3.54-3.64 (m, 4H), 3.45-3.51 (m,1H), 2.39 (dd, J=14.5, 5.5 Hz, 1H), 2.05-2.14 (m, 1H).

Step 7. Synthesis of [cis-7a′-(4-bromo-1,3-thiazol-2-yl)tetrahydro-1′H,3′H-spiro[cyclopropane-1,5′-pyrano[3,4-c][1,2]oxazol]-1′-yl](phenyl)methanone(C61)

Benzoyl peroxide (2.87 g, 11.8 mmol) was added to a solution of C60(4.00 g, 5.92 mmol) in benzene (40 mL) in a microwave vial. The vial wascapped, purged twice with nitrogen, and heated to 105° C. for 2 hours ina microwave reactor. The reaction mixture was then cooled to roomtemperature, diluted with dichloromethane (100 mL) and washed withsaturated aqueous sodium bicarbonate solution (2×100 mL). The combinedaqueous layers were extracted with dichloromethane (2×50 mL), and thecombined organic layers were dried over sodium sulfate, filtered, andconcentrated in vacuo. Silica gel chromatography (Gradient: 0% to 50%ethyl acetate in heptane) provided the product as a white solid. Yield:1.78 g, 4.22 mmol, 71%. LCMS m/z 423.2 (bromine isotope patternobserved) [M+H]⁺. ¹H NMR (400 MHz, CDCl₃), characteristic product peaks:δ: 7.81-7.87 (m, 2H), 7.45-7.51 (m, 1H), 7.38-7.45 (m, 2H), 7.24-7.28(m, 1H), 4.91 (d, J=12.1 Hz, 1H), 4.39 (d, J=12.5 Hz, 1H), 4.19 (dd,J=7.8, 4.7 Hz, 1H), 3.99 (dd, J=7.8, 3.9 Hz, 1H), 3.56-3.65 (m, 1H),2.18 (ddd, J=13.9, 8.8, 1.2 Hz, 1H), 1.76 (dd, J=13.9, 6.5 Hz, 1H),0.85-0.92 (m, 2H, partially obscured by heptane peaks), 0.52-0.62 (m,2H).

Step 8. Synthesis ofcis-7a′-(4-bromo-1,3-thiazol-2-yl)tetrahydro-1′H,3H′-spiro[cyclopropane-1,5′-pyrano[3,4-c][1,2]oxazole](C62)

Lithium hydroxide monohydrate (22.4 g, 507 mmol) was added to a solutionof C61 (1.78 g, 4.22 mmol) in ethanol (125 mL) and water (76 mL). Thereaction mixture was heated at reflux for 24 hours, whereupon it wascooled to room temperature, diluted with saturated aqueous sodiumbicarbonate solution (100 mL), and extracted with dichloromethane (3×100mL). The combined organic layers were dried over sodium sulfate,filtered, and concentrated under reduced pressure to afford the productas a crystalline solid. Yield: 1.06 g, 3.34 mmol, 79%. LCMS m/z 319.1(bromine isotope pattern observed) [M+H]⁺. ¹H NMR (400 MHz, CDCl₃),characteristic product peaks: δ: 7.22 (s, 1H), 6.35-6.61 (br s, 1H),4.03 (d, J=12.1 Hz, 1H), 3.82 (d, J=12.1 Hz, 1H), 3.69-3.80 (m, 2H),3.40-3.50 (m, 1H), 2.21 (d, J=12.5 Hz, 1H), 1.38-1.49 (m, 1H), 0.91-0.98(m, 1H), 0.80-0.87 (m, 1H), 0.53-0.66 (m, 2H).

Step 9. Synthesis ofN-[cis-8a′-(4-bromo-1,3-thiazol-2-yl)-4a′,5′,8′,8a′-tetrahydro-4′H-spiro[cyclopropane-1,6′-pyrano[3,4-d][1,3]thiazin]-2′-yl]benzamide(C63)

A mixture of C62 (1.00 g, 3.15 mmol) and molybdenum hexacarbonyl (0.425g, 1.58 mmol) in acetonitrile (17 mL) and water (1 mL) was heated to 90°C. for 2 hours, whereupon it was cooled to 0° C. and treated with sodiumborohydride (0.477 g, 12.6 mmol). After the reaction mixture had stirredat 0° C. for 1.5 hours, it was filtered through a pad of diatomaceousearth. The filter pad was washed with dichloromethane (3×100 mL), andthe combined filtrates were washed with saturated aqueous sodiumchloride solution (300 mL), dried over sodium sulfate, filtered, andconcentrated in vacuo. The residue was dissolved in methanol (50 mL),stirred for 10 minutes, and concentrated under reduced pressure; thisprocess was repeated two more times. The residue was mixed withdichloromethane (100 mL) and aqueous sodium hydroxide solution (1 M, 100mL), and the biphasic solution was vigorously stirred at roomtemperature for 15 minutes. The organic layer was washed with aqueoussodium hydroxide solution (1 M, 100 mL) and with saturated aqueoussodium chloride solution (100 mL), dried over sodium sulfate, filtered,and concentrated under reduced pressure to provide intermediate[rel-(6R,7R)-6-amino-6-(4-bromo-1,3-thiazol-2-yl)-4-oxaspiro[2.5]oct-7-yl]methanolas a colorless oil (0.96 g). This material was dissolved indichloromethane (20 mL) and treated with benzoyl isothiocyanate (0.424mL, 3.16 mmol); the reaction mixture was stirred at room temperature for16 hours, whereupon it was concentrated in vacuo, providing a yellowsolid (1.45 g). This material was dissolved in 1,2-dichloroethane (30mL) and treated with methoxybenzene (0.979 mL, 9.02 mmol), followed bytrifluoromethanesulfonic acid (0.787 mL, 9.02 mmol). The reactionmixture was stirred at room temperature for 45 minutes, whereupon it wasdiluted with dichloromethane (100 mL) and basified with aqueous sodiumhydroxide solution (1 M, 250 mL). The biphasic solution was allowed tostir at room temperature for 15 minutes, at which time the aqueous layerwas extracted with dichloromethane (2×100 mL). The combined organiclayers were washed with saturated aqueous sodium chloride solution (250mL), dried over sodium sulfate, filtered, and concentrated in vacuo.Silica gel chromatography (Gradient: 0% to 70% ethyl acetate in heptane)provided the product as a white solid. Yield: 0.984 g, 2.12 mmol, 67%.LCMS m/z 466.1 (bromine isotope pattern observed) [M+H]⁺. ¹H NMR (400MHz, CDCl₃), characteristic product peaks: δ: 8.05 (d, J=5.9 Hz, 2H),7.52-7.59 (m, 1H), 7.43-7.50 (m, 2H), 7.24 (s, 1H), 4.02 (d, J=11.3 Hz,1H), 3.82 (d, J=11.3 Hz, 1H), 3.21-3.29 (m, 1H), 3.16 (dd, J=12.9, 3.9Hz, 1H), 2.71 (s, 1H), 2.61 (dd, J=12.9, 2.7 Hz, 1H), 1.09 (dd, J=13.7,4.7 Hz, 1H), 0.94-1.03 (m, 1H), 0.78-0.89 (m, 1H), 0.59-0.69 (m, 1H),0.48-0.58 (m, 1H).

Step 10. Synthesis of N-[cis-8a′-{4-[(2,4-dimethoxybenzyl)amino]-1,3-thiazol-2-yl}-4a′,5′,8′,8a′-tetrahydro-4′H-spiro[cyclopropane-1,6′-pyrano[3,4-d][1,3]thiazin]-2′-yl]benzamide(P17)

A mixture of tris(dibenzylideneacetone)dipalladium(0) (0.101 g, 0.106mmol), di-tert-butyl[2′,4′,6′-tri(propan-2-yl)biphenyl-2-yl]phosphane(0.135 g, 0.318 mmol), and sodium tert-butoxide (0.509 g, 5.29 mmol) waspurged twice with nitrogen. 1,4-Dioxane (9.6 mL) was added, and thereaction mixture was heated to 85° C. (internal) for 5 minutes. Asolution of C63 (0.98 g, 2.12 mmol) and1-(2,4-dimethoxyphenyl)methanamine (0.541 mL, 3.60 mmol) in 1,4-dioxane(9.6 mL) was then added to the reaction mixture, and heating wascontinued at 85° C. (internal) for 25 minutes. The reaction mixture wasquickly cooled to room temperature using a water bath, treated withwater (30 mL) and diatomaceous earth, and filtered through a pad ofdiatomaceous earth. The filter pad was washed with dichloromethane(3×100 mL), and the organic layer from the combined filtrates was washedsequentially with water (2×300 mL), aqueous citric acid solution (5%,2×300 mL), saturated aqueous sodium bicarbonate solution (2×300 mL), andsaturated aqueous sodium chloride solution (500 mL), dried over sodiumsulfate, filtered, and concentrated in vacuo. Silica gel chromatography[Gradient: 20% to 100% (5% triethylamine in ethyl acetate) in heptane]provided the product as an orange solid. Yield: 0.577 g, 1.05 mmol, 50%.LCMS m/z 551.4 [M+H]⁺; ¹H NMR (400 MHz, CDCl₃), characteristic productpeaks: δ 8.14 (d, J=7.4 Hz, 2H), 7.48-7.54 (m, 1H), 7.39-7.46 (m, 2H),7.20 (d, J=8.2 Hz, 1H), 6.42-6.49 (m, 2H), 5.74 (s, 1H), 4.62-4.77 (brs, 1H), 4.20 (s, 2H), 4.02 (d, J=11.7 Hz, 1H), 3.78-3.85 (m, 7H), 3.25(dd, J=12.9, 3.9 Hz, 1H), 3.11-3.20 (m, 1H), 2.73 (s, 1H), 2.57 (dd,J=12.7, 2.9 Hz, 1H), 1.06 (dd, J=13.7, 4.7 Hz, 1H), 0.95-1.03 (m, 1H),0.83 (s, 1H), 0.60-0.67 (m, 1H), 0.47-0.54 (m, 1H).

Preparation P18N-[(4aR,6S,8aR)-8a-(4-Bromo-1,3-thiazol-2-yl)-6-(methoxymethyl)-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P18)

Step 1. Synthesis ofN-[(4aR,6S,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-(hydroxymethyl)-6-{[(4-methoxybenzyl)oxy]methyl}-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(C64)

(7, 7-Dimethyl-2-oxobicyclo[2.2.1]hept-1-yl)methanesulfonic acid(camphorsulfonic acid; 9.3 mg, 0.04 mmol) was added to a mixture of P10(200 mg, 0.40 mmol) and 4-methoxybenzyl-2,2,2-trichloroacetimidate (162mg, 0.56 mmol) in dichloromethane (15 mL). After stirring at roomtemperature for 5 hours, the reaction mixture was diluted with saturatedaqueous sodium bicarbonate solution (15 mL) and extracted with ethylacetate (3×15 mL). The combined organic layers were dried over sodiumsulfate, filtered, and concentrated under reduced pressure; silica gelchromatography (Gradient: 0% to 100% ethyl acetate in heptane) providedthe product as a white solid. Yield: 96 mg, 0.16 mmol 39%. LCMS m/z620.2 [M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ 8.05 (br s, 2H), 7.53-7.60 (m,1H), 7.44-7.51 (m, 2H), 7.20-7.25 (m, 3H), 6.79-6.87 (m, 2H), 4.40-4.57(m, 2H), 4.13-4.20 (m, 2H), 3.80-3.88 (m, 1H), 3.77 (d, J=12.1 Hz, 1H),3.75 (s, 3H), 3.58 (d, J=9.4 Hz, 1H), 3.43 (d, J=9.4 Hz, 1H), 3.12-3.23(m, 2H), 2.57 (dd, J=12.7, 2.2 Hz, 1H), 1.96 (t, J=13.7 Hz, 1H), 1.66(dd, J=13.9, 4.5 Hz, 1H).

Step 2. Synthesis ofN-[(4aR,6S,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-{[(4-methoxybenzyl)oxy]methyl}-6-(methoxymethyl)-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide (C65)

A solution of C64 (438 mg, 0.71 mmol) in tetrahydrofuran (5 mL) wasadded drop-wise to a stirring suspension of sodium hydride (60%dispersion in mineral oil, 70.8 mg, 1.77 mmol) in tetrahydrofuran (10mL) at 0° C. The ice bath was removed and the mixture was stirred atroom temperature for 20 minutes, whereupon it was cooled to 0° C.Iodomethane (66.1 μL, 1.06 mmol) was added, and the ice bath wasremoved. After the reaction mixture had stirred at room temperature for3 hours, it was diluted with saturated aqueous ammonium chloridesolution (25 mL) and water (10 mL). The resulting mixture was extractedwith diethyl ether (3×35 mL), and the combined organic layers were driedover sodium sulfate, filtered, and concentrated in vacuo. Silica gelchromatography (Gradient: 0% to 90% ethyl acetate in heptane) affordedthe product as a white solid. Yield: 356 mg, 0.563 mmol, 80%. LCMS m/z634.3 [M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ 7.90 (br s, 2H), 7.36-7.41 (m,1H), 7.27-7.33 (m, 2H), 7.04-7.08 (m, 3H), 6.61-6.65 (m, 2H), 4.27-4.37(m, 2H), 4.03 (d, J=12.1 Hz, 1H), 3.59-3.69 (m, 2H), 3.55 (s, 3H), 3.36(d, J=9.8 Hz, 1H), 3.26 (s, 3H), 3.24 (s, 1H), 3.22 (d, J=3.1 Hz, 1H),3.10 (dd, J=9.9, 5.3 Hz, 1H), 3.00 (dd, J=12.9, 4.3 Hz, 1H), 2.43 (dd,J=12.9, 2.3 Hz, 1H), 1.87 (t, J=13.7 Hz, 1H), 1.57 (dd, J=14.1, 4.7 Hz,1H).

Step 3. Synthesis ofN-[(4aR,6R,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-(hydroxymethyl)-6-(methoxymethyl)-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(C66)

2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (151 mg, 0.65 mmol) was addedto a mixture of C65 (343 mg, 0.54 mmol) in a mixture of dichloromethaneand water (19:1, 15 mL). After 2.2 hours, the reaction mixture wasdiluted with dichloromethane (30 mL) and filtered through diatomaceousearth. The filtrate was concentrated in vacuo and subjected to silicagel chromatography (Gradient: 0% to 95% ethyl acetate in heptane) toprovide the product as a white solid. Yield: 242 mg, 0.47 mmol, 87%.LCMS m/z 514.1 [M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ 8.08 (br s, 2H),7.53-7.60 (m, 1H), 7.44-7.52 (m, 2H), 7.26 (s, 1H), 4.15-4.23 (m, 1H),3.77-3.83 (m, 2H), 3.65-3.74 (m, 2H), 3.42-3.55 (m, 1H), 3.47 (s, 3H),3.25-3.32 (m, 1H), 3.19 (dd, J=12.9, 4.3 Hz, 1H), 2.64 (d, J=12.9 Hz,1H), 2.12 (d, J=13.3 Hz, 1H), 1.73 (dd, J=13.9, 4.1 Hz, 1H).

Step 4. Synthesis ofN-[(4aR,6S,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-(iodomethyl)-6-(methoxymethyl)-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(C67)

1,1,2,2,3,3,4,4,4-Nonafluorobutane-1-sulfonyl fluoride (0.326 mL, 1.85mmol) was added drop-wise to a solution of triethylamine (295 μL, 2.12mmol) and C66 (271 mg, 0.53 mmol) in acetonitrile (7.5 mL). After thereaction mixture had stirred at room temperature for 70 minutes,potassium iodide (878 mg, 5.29 mmol) was added, and the reaction mixturewas heated at 45° C. for 16 hours. After cooling to room temperature, itwas diluted with water (30 mL) and extracted with diethyl ether (3×30mL). The combined organic layers were washed with saturated aqueoussodium thiosulfate solution (20 mL), dried over sodium sulfate,filtered, and concentrated in vacuo. Silica gel chromatography(Gradient: 0% to 80% ethyl acetate in heptane) provided the product as awhite solid. Yield: 200 mg, 0.32 mmol, 61%. LCMS m/z 624.0 [M+H]⁺. ¹HNMR (400 MHz, CDCl₃) 7.98 (br s, 2H), 7.45-7.62 (m, 3H), 7.26 (s, 1H),4.10-4.20 (m, 1H), 3.74-3.90 (m, 3H), 3.48 (s, 3H), 3.37-3.45 (m, 2H),3.14-3.27 (m, 2H), 2.63 (d, J=12.9 Hz, 1H), 2.02-2.14 (m, 1H), 1.91 (dd,J=13.3, 3.5 Hz, 1H).

Step 5. Synthesis ofN-[(4aR,6S,8aR)-8a-(4-bromo-1,3-thiazol-2-yl)-6-(methoxymethyl)-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(P18)

A solution of lithium triethylborohydride in tetrahydrofuran (1.0 M,3.46 mL, 3.46 mmol) was added drop-wise to a 0° C. solution of C67 (196mg, 0.32 mmol) in tetrahydrofuran (6 mL). The ice bath was removed uponcompletion of the addition, and the reaction mixture was allowed to warmto room temperature over 10 minutes. The reaction mixture was thenheated at reflux for 5.5 hours, whereupon it was allowed to cool to roomtemperature, and carefully diluted with saturated aqueous sodiumbicarbonate solution (25 mL). The resulting mixture was extracted withethyl acetate (3×25 mL), and the combined organic layers were dried oversodium sulfate, filtered and concentrated in vacuo. The residue wasdissolved in methanol and heated at reflux for 1.2 hours, allowed tocool to ambient temperature, and then concentrated under reducedpressure. Purification via silica gel chromatography (Gradient: 0% to100% ethyl acetate in heptane) afforded the product as a colorlesssolid. Yield: 52.2 mg, 0.11 mmol, 33%. LCMS m/z 498.2 [M+H]⁺. ¹H NMR(400 MHz, CDCl₃) δ 7.90-8.25 (br m, 2H), 7.42-7.58 (m, 3H), 7.22 (s,1H), 4.10-4.30 (br m, 1H), 3.73 (d, J=12.1 Hz, 1H), 3.61-3.65 (m, 2H),3.45 (s, 3H), 3.10-3.31 (m, 2H), 2.58 (d, J=12.9 Hz, 1H), 1.86-2.01 (m,1H), 1.74 (d, J=11.4 Hz, 1H), 1.29 (s, 3H).

Preparation P19 5-(Difluoromethoxy)pyridine-2-carboxylic acid (P19)

Step 1. Synthesis of methyl 5-(difluoromethoxy)pyridine-2-carboxylate(C68)

Potassium carbonate (45.1 g, 326 mmol) was added to a solution of methyl5-hydroxypyridine-2-carboxylate (20 g, 130 mmol) inN,N-dimethylformamide (500 mL), and the reaction mixture was stirred atroom temperature for 0.5 hours. Sodium chloro(difluoro)acetate (63.7 g,418 mmol) was introduced, and the resulting mixture was heated at 100°C. for 5 hours, whereupon it was partitioned between saturated aqueoussodium chloride solution (300 mL) and ethyl acetate (300 mL). Theaqueous layer was extracted with ethyl acetate (3×200 mL), and thecombined organic layers were washed with saturated aqueous sodiumchloride solution (2×200 mL), dried, filtered, and concentrated invacuo. Silica gel chromatography (Eluent: 5:1 petroleum ether/ethylacetate) afforded the product as a pale yellow oil. Yield: 17 g, 84mmol, 65%. ¹H NMR (400 MHz, CDCl₃) δ 8.56 (s, 1H), 8.17 (d, J=8.7 Hz,1H), 7.59 (br d, J=8.7 Hz, 1H), 6.64 (t, J_(HF)=71.9 Hz, 1H), 4.00 (s,3H).

Step 2. Synthesis of 5-(difluoromethoxy)pyridine-2-carboxylic acid (P19)

A solution of C68 (17 g, 84 mmol) in tetrahydrofuran (100 mL) and water(50 mL) was cooled to 0° C. and treated with lithium hydroxide (6.0 g,250 mmol). After the reaction mixture had stirred at room temperaturefor 2 hours, it was acidified to a pH of 3 with 1 M aqueous hydrochloricacid. The aqueous layer was extracted with ethyl acetate (3×100 mL), andthe combined organic layers were washed with saturated aqueous sodiumchloride solution (100 mL), dried, filtered, and concentrated underreduced pressure to provide the product as a white solid. Yield: 13 g,69 mmol, 82%. LCMS m/z 189.8 [M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ 8.52 (d,J=2.4 Hz, 1H), 8.29 (d, J=8.5 Hz, 1H), 7.73 (dd, J=8.6, 2.4 Hz, 1H),6.68 (t, J_(HF)=71.5 Hz, 1H).

Preparation P20 5-(Difluoromethoxy)-3-methylpyridine-2-carboxylic acid(P20)

Step 1. Synthesis of 3-methyl-5-nitropyridine-2-carbonitrile (C69)

A mixture of 3-methylpyridine-2-carbonitrile (128 g, 1.08 mol) andtetrabutylammonium nitrate (363 g, 1.19 mol) in tert-butyl methyl ether(1.3 L) was cooled to 4° C. Trifluoroacetic anhydride (171 mL, 1.21 mol)was added, and the reaction mixture was allowed to stir at roomtemperature for 60 hours. It was then adjusted to a pH of approximately7 by addition of 20% aqueous sodium hydroxide solution, and extractedwith dichloromethane (3×1 L). The combined organic layers were dried,filtered, and concentrated in vacuo; purification via silica gelchromatography (Gradient: 0% to 10% ethyl acetate in petroleum ether)afforded the product as a yellow solid. Yield: 70 g, 0.43 mmol, 40%. ¹HNMR (400 MHz, CDCl₃) δ 9.31-9.36 (m, 1H), 8.47-8.52 (m, 1H), 2.74 (s,3H).

Step 2. Synthesis of 5-amino-3-methylpyridine-2-carbonitrile (C70)

To a solution of C69 (40.0 g, 245 mmol) in ethanol (630 mL) and water(70 mL) was added calcium chloride (13.6 g, 123 mmol), followed by ironpowder (123 g, 2.20 mol), and the reaction mixture was stirred overnightat room temperature. After filtration of the reaction mixture, thefiltrate was concentrated in vacuo, and the residue was purified bychromatography on silica gel (Gradient: 10% to 50% ethyl acetate inpetroleum ether). The product was obtained as a yellow solid. Yield:20.0 g, 150 mmol, 61%. ¹H NMR (400 MHz, CDCl₃) δ 7.94 (d, J=2.5 Hz, 1H),6.81 (d, J=2.5 Hz, 1H), 4.07-4.19 (br s, 2H), 2.45 (s, 3H).

Step 3. Synthesis of 5-hydroxy-3-methylpyridine-2-carbonitrile (C71)

Sodium nitrite (1.6 M aqueous solution containing 10.3 g of sodiumnitrite, 149 mmol) was slowly added to a 0° C. solution of C70 (18.0 g,135 mmol) in water (243 mL) and concentrated sulfuric acid (67.5 mL).The reaction mixture was warmed to room temperature and then stirred at100° C. for 3 hours, whereupon it was cooled and extracted with ethylacetate (3×75 mL). The combined organic layers were washed with water(2×75 mL) and with saturated aqueous sodium chloride solution (2×75 mL),dried, filtered, and concentrated under reduced pressure to afford theproduct as a yellow solid. Yield: 16 g, 120 mmol, 89%. ¹H NMR (400 MHz,DMSO-d₆) δ 11.07 (br s, 1H), 8.08 (d, J=2.6 Hz, 1H), 7.20 (d, J=2.3 Hz,1H), 2.40 (s, 3H).

Step 4. Synthesis of 5-(difluoromethoxy)-3-methylpyridine-2-carbonitrile(C72)

A mixture of C71 (5.70 g, 42.5 mmol), sodium chlorodifluoroacetate (13.0g, 85.3 mmol), and potassium carbonate (17.6 g, 127 mmol) inN,N-dimethylformamide (175 mL) was stirred for 30 minutes at 100° C. Thereaction mixture was then diluted with ethyl acetate (400 mL), andsequentially washed with saturated aqueous ammonium chloride solution(3×200 mL) and saturated aqueous sodium chloride solution (3×200 mL).The combined aqueous layers were extracted with ethyl acetate (200 mL),and the combined organic layers were dried over sodium sulfate,filtered, and concentrated in vacuo. Silica gel chromatography(Gradient: 5% to 15% ethyl acetate in petroleum ether) provided theproduct as a colorless oil. Yield: 3.9 g, 21 mmol, 49%. ¹H NMR (400 MHz,CDCl₃) δ 8.39 (br d, J=2.1 Hz, 1H), 7.47-7.43 (m, 1H), 6.64 (t,J_(HF)=71.5 Hz, 1H), 2.59 (s, 3H).

Step 5. Synthesis of 5-(difluoromethoxy)-3-methylpyridine-2-carboxylicacid (P20)

Aqueous sodium hydroxide solution (1 M, 124 mL, 124 mmol) was added to asolution of C72 (7.60 g, 41.3 mmol) in ethanol (200 mL), and thereaction mixture was stirred for 16 hours at 70° C. It was then dilutedwith tert-butyl methyl ether (200 mL) and extracted with water (2×100mL). The combined aqueous layers were washed with tert-butyl methylether (100 mL), acidified to pH 2 with 1 M aqueous hydrochloric acid,and extracted with tert-butyl methyl ether (2×200 mL). The combinedorganic extracts were dried over sodium sulfate, filtered, andconcentrated in vacuo to afford the product as a white solid. Yield: 6.6g, 32 mmol, 77%. LCMS m/z 203.7 [M+H]⁺. ¹H NMR (400 MHz, CD₃OD) δ 8.32(br d, J=2.1 Hz, 1H), 7.58-7.62 (m, 1H), 7.06 (t, J_(HF)=72.7 Hz, 1H),2.64 (s, 3H).

Preparation P21 3-Chloro-5-(difluoromethoxy)pyridine-2-carboxylic acid(P21)

Step 1. Synthesis of 5, 6-dichloropyridine-3-diazonium tetrafluoroborate(C73)

To a 0° C. solution of 5,6-dichloropyridin-3-amine (15 g, 92 mmol) intetrafluoroboric acid (˜45% in water; 150 mL) was added a solution ofsodium nitrite (6.67 g, 96.6 mmol) in water (90 mL) in a drop-wisemanner, during which time the diazonium salt precipitated. Aftercompletion of the addition, the reaction mixture was stirred at 0° C.for 1 hour. It was then filtered; the filter cake was washed withpetroleum ether (3×200 mL) to afford the product (25.8 g) as a pale redsolid. This material was used directly in the next step.

Step 2. Synthesis of 5,6-dichloropyridin-3-yl acetate (C74)

Compound C73 (from the previous step; 25.8 g, 92 mmol) was dissolved inacetic anhydride (75 mL) and slowly warmed to 70° C. When nitrogenevolution had ceased, stirring was continued for 1 hour at 70° C.,whereupon the solvent was evaporated. The residue was dissolved intert-butyl methyl ether (100 mL) and washed with water (4×40 mL). Thecombined aqueous layers were extracted with additional tert-butyl methylether (3×50 mL), and the combined organic layers were washed withsaturated aqueous sodium chloride solution (5×20 mL), dried over sodiumsulfate, filtered, and concentrated in vacuo. Silica gel chromatography(Gradient: 0% to 25% ethyl acetate in petroleum ether) afforded theproduct as a yellow oil. Yield: 9.7 g, 47 mmol, 51% over 2 steps. ¹H NMR(400 MHz, DMSO-d₆) δ 8.33 (d, J=2.5 Hz, 1H), 8.18 (d, J=2.5 Hz, 1H),2.32 (s, 3H).

Step 3. Synthesis of 3-chloro-5-hydroxypyridine-2-carbonitrile (C75)

Zinc cyanide (2.6 g, 22 mmol), zinc dust (145 mg, 2.21 mmol), and[1,1′-bis(diphenylphosphino)ferrocene]dichloropalladium(II) (1.72 g,2.35 mmol) were added to a room temperature solution of C74 (9.7 g, 47mmol) in N,N-dimethylformamide (60 mL). The reaction mixture was stirredat 140° C. for 13 hours, whereupon it was diluted with tert-butyl methylether (200 mL) and water (150 mL) and filtered through a pad ofdiatomaceous earth. The aqueous layer of the filtrate was extracted withadditional tert-butyl methyl ether (3×50 mL), and the combined organiclayers were washed with saturated aqueous sodium chloride solution (8×50mL), dried over sodium sulfate, filtered, and concentrated in vacuo toprovide the product as a brown solid. Yield: 6.8 g, 44 mmol, 94%. ¹H NMR(400 MHz, CD₃OD) δ 8.16 (d, J=2.5 Hz, 1H), 7.38 (d, J=2.5 Hz, 1H).

Step 4. Synthesis of 3-chloro-5-(difluoromethoxy)pyridine-2-carbonitrile(C76)

A mixture of C75 (6.8 g, 44 mmol), sodium chloro(difluoro)acetate (20 g,180 mmol) and potassium carbonate (36.5 g, 264 mmol) inN,N-dimethylformamide (70 mL) was stirred at 100° C. for 40 minutes(until no gas evolution could be seen). The reaction mixture was dilutedwith tert-butyl methyl ether (200 mL) and water (150 mL), and theaqueous layer was extracted with additional tert-butyl methyl ether(3×100 mL). The combined organic layers were washed with saturatedaqueous sodium chloride solution (8×50 mL), dried over sodium sulfate,filtered, and concentrated under reduced pressure. Chromatography onsilica gel (Gradient: 0% to 20% ethyl acetate in petroleum ether)afforded the product as a yellow oil. Yield: 5.55 g, 27.1 mmol, 62%. ¹HNMR (400 MHz, CDCl₃) δ 8.52-8.45 (m, 1H), 7.73-7.65 (m, 1H), 6.68 (t,J_(HF)=70.8 Hz, 1H).

Step 5. Synthesis of methyl3-chloro-5-(difluoromethoxy)pyridine-2-carboxylate (C77)

Compound C76 (4.82 g, 23.6 mmol) was dissolved in a solution of hydrogenchloride in methanol (4 M; 75 mL), and the reaction mixture was stirredat 60° C. for 13 hours. It was then diluted with water (50 mL) andstirred at room temperature for 30 minutes. The mixture was concentratedunder reduced pressure and the residual aqueous phase was neutralizedvia addition of saturated aqueous sodium bicarbonate solution (200 mL)and then extracted with ethyl acetate (3×60 mL). The combined organiclayers were washed with saturated aqueous sodium chloride solution (30mL), dried over sodium sulfate, filtered, and concentrated in vacuo. Theresulting material was combined with the crude product from a similarreaction carried out using C76 (500 mg, 2.4 mmol), and the mixture wassubjected to silica gel chromatography (Gradient: 0% to 20% ethylacetate in petroleum ether), providing the product as a yellow oil,which solidified upon standing at room temperature. Yield: 3.4 g, 14mmol, 54%. ¹H NMR (400 MHz, CDCl₃) δ 8.50-8.43 (m, 1H), 7.68-7.62 (m,1H), 6.64 (t, J_(HF)=71.3 Hz, 1H), 4.02 (s, 3H).

Step 6. Synthesis of 3-chloro-5-(difluoromethoxy)pyridine-2-carboxylicacid (P21)

Lithium hydroxide monohydrate (279 mg, 6.31 mmol) was added to asolution of C77 (1.0 g, 4.2 mmol) in tetrahydrofuran (40 mL) and water(20 mL). The reaction mixture was stirred at room temperature for 3hours, whereupon it was concentrated in vacuo, and the residual aqueousphase was adjusted to a pH of 2-3 via addition of 2 M aqueoushydrochloric acid. The resulting mixture was extracted with ethylacetate (7×20 mL), and the combined organic layers were dried oversodium sulfate, filtered, and concentrated under reduced pressure toafford the product as a pale yellow solid. Yield: 720 mg, 3.22 mmol,77%. LCMS m/z 222.0 (chlorine isotope pattern observed) [M−H⁺]. ¹H NMR(400 MHz, DMSO-d₆) δ 8.51 (d, J=2.0 Hz, 1H), 8.06 (d, J=2.0 Hz, 1H),7.44 (t, J_(HF)=72.8 Hz, 1H).

Preparation P22 2-(Fluoromethyl)-1,3-oxazole-4-carboxylic acid (P22)

Step 1. Synthesis of methyl2-(dichloromethyl)-4,5-dihydro-1,3-oxazole-4-carboxylate (C78)

A solution of dichloroacetonitrile (215 g, 1.96 mol) in methanol (200mL) was added drop-wise to a −5° C. solution of sodium methoxide (15.4g, 0.285 mol) in methanol (500 mL). A solution of methyl2-amino-3-hydroxypropanoate, hydrochloride salt (382 g, 2.45 mol) inmethanol (300 mL) was then added to the −5° C. reaction mixture, whichwas subsequently allowed to stir at room temperature for 16 hours.Dichloromethane (1 L) and water (800 mL) were added, and the aqueouslayer was extracted with dichloromethane (1 L); the combined organiclayers were concentrated in vacuo to provide the product as a yellowoil, which was used in the next step without further purification.Yield: 300 g, 1.4 mol, 71%. ¹H NMR (400 MHz, CDCl₃) δ 6.29 (s, 1H), 4.90(dd, J=10.8, 8.3 Hz, 1H), 4.74 (dd, J=8.8, 8.3 Hz, 1H), 4.66 (dd,J=10.8, 8.9 Hz, 1H), 3.82 (s, 3H).

Step 2. Synthesis of methyl2-(chloromethyl)-4-methoxy-4,5-dihydro-1,3-oxazole-4-carboxylate (C79)

A solution of C78 (205 g, 0.967 mol) in methanol (700 mL) was addeddrop-wise to a cooled solution of sodium methoxide (52.2 g, 0.966 mol)in methanol (300 mL), at a rate sufficient to maintain the reactiontemperature below 10° C. The reaction mixture was then stirred at roomtemperature for 16 hours, whereupon it was diluted with dichloromethane(1 L) and water (800 mL). The aqueous layer was extracted withdichloromethane (2×500 mL), and the combined organic layers wereconcentrated in vacuo to afford the product as a yellow oil. Thismaterial was used in the next step without additional purification.Yield: 200 g, 0.96 mol, 99%.

Step 3. Synthesis of methyl 2-(chloromethyl)-1,3-oxazole-4-carboxylate(C80)

(7,7-Dimethyl-2-oxobicyclo[2.2.1]hept-1-yl)methanesulfonic acid(camphorsulfonic acid, 45.9 g, 0.198 mol) was added to a solution of C79(193 g, 0.930 mol) in toluene (700 mL), and the reaction mixture washeated at 70° C. for 1 hour. Water (1 L) was added, and the mixture wasextracted with ethyl acetate (2×1 L); the combined organic layers weresequentially washed with aqueous potassium carbonate solution (10%, 500mL), water (800 mL), and saturated aqueous sodium chloride solution (0.8L), dried, and concentrated in vacuo. Silica gel chromatography(Gradient: 5% to 25% ethyl acetate in petroleum ether) provided theproduct as a white solid. Yield: 55 g, 0.31 mol, 33%. ¹H NMR (400 MHz,CDCl₃) δ 8.26 (s, 1H), 4.65 (s, 2H), 3.93 (s, 3H).

Step 4. Synthesis of methyl 2-(fluoromethyl)-1,3-oxazole-4-carboxylate(C81)

To a suspension of C80 (40 g, 0.23 mol) in acetonitrile (1 L) was addedtetrabutylammonium fluoride (357 g, 1.36 mol), and the reaction mixturewas stirred at 25° C. for 16 hours. After removal of solvent in vacuo,the residue was diluted with water (1 L) and extracted with ethylacetate (4×1 L). The combined organic layers were dried over sodiumsulfate, filtered, and concentrated under reduced pressure.Chromatography on silica gel (Gradient: 17% to 23% ethyl acetate inpetroleum ether) afforded the product as a yellow solid. Yield: 8.7 g,55 mmol, 24%. ¹H NMR (400 MHz, CDCl₃) δ 8.31 (d, J=1.2 Hz, 1H), 5.43 (d,J_(HF)=47.2 Hz, 2H), 3.94 (s, 3H).

Step 5. Synthesis of 2-(fluoromethyl)-1,3-oxazole-4-carboxylic acid(P22)

To a solution of C81 (18 g, 110 mmol) in tetrahydrofuran (150 mL) wasadded a solution of lithium hydroxide (5.42 g, 226 mmol) in a mixture ofmethanol and water (1:1, 500 mL). The reaction mixture was stirred atroom temperature for 1 hour, whereupon it was concentrated in vacuo.After the residue had been dissolved in water (500 mL), it was acidifiedby addition of 2 M aqueous hydrochloric acid until it reached a pH of 2.The aqueous layer was then extracted with ethyl acetate (2×100 mL), andthe combined organic layers were dried over sodium sulfate, filtered,and concentrated under reduced pressure, providing the product as ayellow solid. Yield: 13 g, 90 mmol, 82%. LCMS m/z 144.0 [M−H⁺]. ¹H NMR(400 MHz, CD₃OD) δ 8.61 (s, 1H), 5.47 (d, J_(HF)=47 Hz, 2H).

Examples 1 and 2N-{2-[(4aS,8aS)-2-Amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyridine-2-carboxamide(1) andN-{2-[(4aR,8aR)-2-Amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyridine-2-carboxamide(2)

Step 1. Synthesis of methyl 5-(but-2-yn-1-yloxy)pyridine-2-carboxylate(C82)

To a 0° C. solution of but-2-yn-1-ol (0.645 mL, 8.62 mmol) intetrahydrofuran (30 mL) were added methyl5-hydroxypyridine-2-carboxylate (1.30 g, 8.49 mmol), triphenylphosphine(3.34 g, 12.7 mmol), and diisopropyl azodicarboxylate (2.50 mL, 12.7mmol). The reaction mixture was then warmed to room temperature (18° C.)and stirred for 48 hours, whereupon it was concentrated in vacuo. Silicagel chromatography (Gradient: 15% to 50% ethyl acetate in petroleumether) afforded the product as a yellow solid. Yield: 1.1 g, 5.4 mmol,64%. ¹H NMR (400 MHz, CDCl₃) δ 8.46 (d, J=2.9 Hz, 1H), 8.13 (d, J=8.8Hz, 1H), 7.37 (dd, J=8.8, 2.9 Hz, 1H), 4.77 (q, J=2.3 Hz, 2H), 3.99 (s,3H), 1.86 (t, J=2.3 Hz, 3H).

Step 2. Synthesis of 5-(but-2-yn-1-yloxy)pyridine-2-carboxylic acid(C83)

A solution of lithium hydroxide monohydrate (975 mg, 23.2 mmol) in water(7 mL) was added drop-wise to a room temperature (15° C.) solution ofC82 (1.59 g, 7.75 mmol) in tetrahydrofuran (20 mL), and the reactionmixture was stirred at room temperature for 1 hour. It was thenacidified to pH 2 via addition of 2 M aqueous hydrochloric acid, andextracted with ethyl acetate (2×100 mL). The combined organic layerswere washed with saturated aqueous sodium chloride solution (2×100 mL),dried over sodium sulfate, filtered, and concentrated under reducedpressure to provide the product as a yellow solid. Yield: 1.0 g, 5.2mmol, 67%. LCMS m/z 192.1 [M+H]⁺. ¹H NMR (400 MHz, CD₃OD) δ 8.35 (d,J=2.9 Hz, 1H), 8.14 (d, J=8.7 Hz, 1H), 7.57 (dd, J=8.7, 2.8 Hz, 1H),4.87 (q, J=2.3 Hz, 2H), 1.84 (t, J=2.3 Hz, 3H).

Step 3. Synthesis ofN-{2-[cis-2-(benzoylamino)-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyridine-2-carboxamide(C84)

Pyridine (114 mg, 1.44 mmol) and2,4,6-tripropyl-1,3,5,2,4,6-trioxatriphosphinane 2,4,6-trioxide (50%solution in ethyl acetate; 690 mg, 1.08 mmol) were added to a mixture ofP1 (150 mg, 0.37 mmol) and C83 (87 mg, 0.46 mmol) in ethyl acetate (20mL). The reaction mixture was stirred at 40° C. for 16 hours, whereuponit was concentrated under reduced pressure to provide the product as ayellow oil, which was used directly in the next step without additionalpurification. LCMS m/z 576.1 [M+H]⁺.

Step 4. Synthesis ofN-{2-[cis-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyridine-2-carboxamide(C85)

A mixture of C84 (from the previous step; ≦0.37 mmol), methoxylaminehydrochloride (301 mg, 3.60 mmol), and pyridine (2.85 g, 36.0 mmol) inethanol (25 mL) was stirred at 60° C. for 16 hours. The reaction mixturewas then concentrated in vacuo and purified by reversed phase HPLC(Column: Phenomenex Gemini C18, 8 μm; Mobile phase A: aqueous ammonia,pH 10; Mobile phase B: acetonitrile; Gradient: 36% to 56% B), affordingthe product as a white solid. Yield: 69 mg, 0.15 mmol, 40% over 2 steps.LCMS m/z 472.1 [M+H]⁺.

Step 5. Isolation ofN-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyridine-2-carboxamide(1) andN-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyridine-2-carboxamide(2)

Racemic C85 (from the previous step, 69 mg) was separated into itscomponent enantiomers via two separations using supercritical fluidchromatography [Column: Chiral Technologies Chiralpak AD, 10 μm; Mobilephase: 55:45 carbon dioxide/(ethanol containing 0.1% ammoniumhydroxide)]. The first-eluting enantiomer was 1, isolated as a whitesolid. Yield: 19 mg, 28% from the supercritical fluid chromatography.LCMS m/z 472.0 [M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ 10.41 (br s, 1H), 8.35(d, J=2.4 Hz, 1H), 8.24 (d, J=8.3 Hz, 1H), 7.68 (s, 1H), 7.45 (dd,J=8.4, 2.6 Hz, 1H), 4.81-4.77 (m, 2H), 4.10 (d, J=11.7 Hz, 1H), 3.73 (d,J=11.7 Hz, 1H), 3.21 (dd, J=12, 4 Hz, 1H), 3.03-2.94 (m, 1H), 2.55 (brd, J=12.5 Hz, 1H), 1.96 (dd, J=13.6, 13.3 Hz, 1H), 1.90-1.86 (m, 3H),1.46 (s, 3H), 1.38 (dd, J=13.5, 4 Hz, 1H), 1.33 (s, 3H).

The second-eluting enantiomer, also obtained as a white solid, was 2.Yield: 21 mg, 30% from the supercritical fluid chromatography. LCMS m/z472.0 [M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ 10.41 (br s, 1H), 8.35 (d, J=2.5Hz, 1H), 8.24 (d, J=8.6 Hz, 1H), 7.68 (s, 1H), 7.45 (dd, J=8.5, 2.5 Hz,1H), 4.81-4.77 (m, 2H), 4.10 (d, J=11.6 Hz, 1H), 3.73 (d, J=11.4 Hz,1H), 3.21 (dd, J=12, 4 Hz, 1H), 3.03-2.94 (m, 1H), 2.55 (br d, J=12.3Hz, 1H), 1.96 (dd, J=13.3, 13.3 Hz, 1H), 1.91-1.86 (m, 3H), 1.46 (s,3H), 1.38 (dd, J=13, 3.5 Hz, 1H), 1.33 (s, 3H).

The absolute configuration of the more potent enantiomer 2 (see Table 2)was assigned in analogy with the work reported by C. R. Butler et al.,J. Med. Chem. 2015, 58, 2678-2702, and M. A. Brodney, J. Med. Chem.2015, 58, 3223-3252. This rationale was applied in assigning absolutestereochemistry to all of the enantiomer pairs obtained herein.

Alternate Synthesis of Example 2N-{2-[(4aR,8aR)-2-Amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyridine-2-carboxamide(2)

Step 1. Synthesis ofN-{2-[(4aR,8aR)-2-(benzoylamino)-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyridine-2-carboxamide(C86)

To a solution of C83 (40 mg, 0.21 mmol) in dichloromethane (15 mL) wereadded O-(7-azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluroniumhexafluorophosphate (HATU; 92 mg, 0.24 mmol) and triethylamine (32 mg,0.32 mmol) at room temperature (−17° C.). After the reaction mixture hadstirred at room temperature for 30 minutes, P2 (86% purity; 80 mg, 0.17mmol) was added in one portion, and stirring was continued for 18 hoursat 25° C. The reaction mixture was combined with material from a similarreaction carried out using P2 (20 mg of 86% purity; 43 μmol), and theresulting solution was diluted with dichloromethane (50 mL) and washedwith saturated aqueous sodium chloride solution (2×30 mL). The combinedaqueous layers were extracted with dichloromethane (30 mL); the combinedorganic layers were dried over sodium sulfate, filtered, andconcentrated in vacuo to afford the product as a yellow solid. Thismaterial was taken directly to the following step, without additionalpurification. LCMS m/z 576.1 [M+H]⁺.

Step 2. Synthesis ofN-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyridine-2-carboxamide(2)

Methoxylamine hydrochloride (179 mg, 2.14 mmol) and pyridine (1.69 g,21.4 mmol) were added to a suspension of C86 (from the previous step;≦0.21 mmol) in ethanol (25 mL), and the reaction mixture was stirred at60° C. for 12 hours. After the reaction mixture had been concentrated invacuo, the residue was purified via reversed phase HPLC (Column:Phenomenex Gemini C18, 5 μm; Mobile phase A: 0.05% ammonia in water;Mobile phase B: acetonitrile; Gradient: 42% to 62% B), providing theproduct as an off-white solid. Yield: 63 mg, 0.13 mmol, 62% over 2steps. LCMS m/z 472.0 [M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ 10.41 (br s,1H), 8.35 (d, J=2.5 Hz, 1H), 8.24 (d, J=8.7 Hz, 1H), 7.68 (s, 1H), 7.45(dd, J=8.8, 2.8 Hz, 1H), 4.9-4.3 (br s, 2H), 4.79 (br q, J=2 Hz, 2H),4.10 (d, J=11.5 Hz, 1H), 3.73 (d, J=11.5 Hz, 1H), 3.21 (dd, J=12.7, 4.1Hz, 1H), 3.02-2.94 (m, 1H), 2.54 (dd, J=12.4, 2.5 Hz, 1H), 1.96 (dd,J=13.4, 13.4 Hz, 1H), 1.88 (t, J=2.2 Hz, 3H), 1.45 (s, 3H), 1.38 (dd,J=13.4, 4.1 Hz, 1H), 1.33 (s, 3H).

Examples 3, 4, and 5N-{2-[cis-2′-Amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide(3),N-{2-[(4a′S,8a′S)-2′-Amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide(4), andN-{2-[(4a′R,8a′R)-2′-Amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide(5)

Step 1. Synthesis ofN-{2-[cis-2′-(benzoylamino)-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)-N-(2,4-dimethoxybenzyl)pyridine-2-carboxamide(C87)

Triethylamine (0.295 mL, 2.12 mmol) was added to a mixture of P19 (0.161g, 0.851 mmol) in ethyl acetate (1 mL). The resulting solution wastreated with 2,4,6-tripropyl-1,3,5,2,4,6-trioxatriphosphinane2,4,6-trioxide (50% solution in ethyl acetate; 3.48 mL, 5.85 mmol), andthe reaction mixture was heated at 65° C. for 20 minutes. Compound P4(300 mg, 0.531 mmol) was then added, and stirring was continued for 16hours at 65° C. After the reaction mixture had cooled to roomtemperature, it was diluted with ethyl acetate (100 mL) and washed withwater (2×150 mL). The organic layer was then sequentially washed withsaturated aqueous sodium bicarbonate solution (250 mL; the resultingaqueous wash was found to exhibit a pH of 8) and saturated aqueoussodium chloride solution (250 mL), dried over sodium sulfate, filtered,and concentrated in vacuo. Silica gel chromatography (Gradient: 0% to100% ethyl acetate in heptane) afforded the product as a yellow solid.Yield: 248 mg, 0.337 mmol, 63%. ¹H NMR (400 MHz, CDCl₃), characteristicpeaks: δ 7.79 (d, J=8.6 Hz, 1H), 7.58-7.49 (m, 2H), 7.49-7.40 (m, 2H),6.59 (t, J_(HF)=72.0 Hz, 1H), 6.47-6.35 (m, 2H), 5.25-5.04 (m, 2H), 3.79(s, 3H), 3.70 (s, 3H), 2.89 (br d, J=12 Hz, 1H), 2.46 (br d, J=13 Hz,1H).

Step 2. Synthesis ofN-{2-[cis-2′-(benzoylamino)-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide(C88)

Trifluoroacetic acid (1.3 mL, 17 mmol) was added to a solution of C87(247 mg, 0.336 mmol) in dichloromethane (17 mL), and the reactionmixture was allowed to stir at room temperature for 16 hours, whereuponit was partitioned between aqueous sodium bicarbonate solution (100 mL)and dichloromethane (50 mL). The aqueous layer was extracted withdichloromethane (2×50 mL), and the combined organic layers were washedwith saturated aqueous sodium chloride solution (150 mL), dried oversodium sulfate, and filtered. The filtrate was adsorbed onto silica geland subjected to silica gel chromatography (Gradient: 0% to 80% ethylacetate in heptane), providing the product as a white solid. Yield: 158mg, 0.270 mmol, 80%. ¹H NMR (400 MHz, CDCl₃) δ 10.43 (br s, 1H), 8.50(d, J=2.6 Hz, 1H), 8.33 (d, J=8.6 Hz, 1H), 8.15-8.07 (m, 2H), 7.77 (s,1H), 7.69 (dd, J=8.6, 2.6 Hz, 1H), 7.57-7.51 (m, 1H), 7.50-7.43 (m, 2H),6.66 (t, J_(HF)=71.9 Hz, 1H), 3.85 (AB quartet, upfield doublet isbroadened, J_(AB)=12.1 Hz, Δν_(AB)=81 Hz, 2H), 3.22 (dd, J=12.5, 4 Hz,1H), 3.09-3.00 (m, 1H), 2.61 (dd, J=13, 2 Hz, 1H), 2.32-1.97 (m, 5H),1.94-1.82 (m, 2H), 1.77-1.63 (m, 1H).

Step 3. Synthesis ofN-{2-[cis-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide(3)

To a solution of C88 (158 mg, 0.270 mmol) in dichloromethane (5 mL) wasadded ethanol (0.158 mL, 2.71 mmol), followed by hydrazine monohydrate(0.143 mL, 2.95 mmol), and the reaction mixture was allowed to stir atroom temperature for 16 hours. It was then concentrated under reducedpressure, dissolved in dichloromethane (10 mL), and adsorbed onto silicagel after addition of a small amount of methanol and ethyl acetate.Silica gel chromatography (Gradient: 0% to 10% methanol indichloromethane) afforded a white solid, which was triturated withdichloromethane (5 mL) to provide, after washing with dichloromethane(2×3 mL), the product as a white solid (40 mg). The filtrate from thetrituration was concentrated in vacuo and triturated withdichloromethane (3 mL), providing additional product as a white solid.Combined yield: 75 mg, 0.16 mmol, 59%. LCMS m/z 482.3 [M+H]⁺. ¹H NMR(400 MHz, CDCl₃) δ 10.40 (br s, 1H), 8.49 (dd, J=2.7, 0.5 Hz, 1H), 8.32(dd, J=8.6, 0.6 Hz, 1H), 7.73 (s, 1H), 7.68 (br dd, J=8.6, 2.6 Hz, 1H),6.66 (t, J_(HF)=71.9 Hz, 1H), 3.83 (AB quartet, upfield doublet isbroadened, J_(AB)=11.4 Hz, Δν_(AB)=43 Hz, 2H), 3.22 (dd, J=12.6, 4.1 Hz,1H), 2.93-2.85 (m, 1H), 2.61 (dd, J=12.5, 2.7 Hz, 1H), 2.33-2.14 (m,3H), 2.04-1.95 (m, 2H), 1.92-1.81 (m, 1H), 1.75 (dd, J=13.4, 4.0 Hz,1H), 1.73-1.61 (m, 1H).

Step 4. Isolation ofN-{2-[(4a′S,8a′S)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide(4) andN-{2-[(4a′R,8a′R)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide(5)

Racemic 3 (from the previous step, 75 mg) was separated into itscomponent enantiomers via supercritical fluid chromatography [Column:Chiral Technologies Chiralcel OJ-H, 5 μm; Mobile phase: 9:1 carbondioxide/(methanol containing 0.2% ammonium hydroxide)]. Thefirst-eluting enantiomer was 4. Yield: 21 mg, 28% from the supercriticalfluid chromatography. LCMS m/z 482.3 [M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ10.40 (br s, 1H), 8.49 (dd, J=2.6, 0.5 Hz, 1H), 8.32 (dd, J=8.6, 0.6 Hz,1H), 7.76 (s, 1H), 7.68 (br dd, J=8.6, 2.7 Hz, 1H), 6.66 (t, J_(HF)=71.9Hz, 1H), 3.92-3.82 (m, 2H), 3.25 (dd, J=12.7, 4.2 Hz, 1H), 3.02-2.92 (m,1H), 2.66 (br d, J=12.8 Hz, 1H), 2.35-2.14 (m, 3H), 2.09-1.75 (m, 4H),1.74-1.61 (m, 1H).

The second-eluting enantiomer was 5. Yield: 14 mg, 19% from thesupercritical fluid chromatography. LCMS m/z 482.1 [M+H]⁺. ¹H NMR (400MHz, CDCl₃) δ 10.40 (br s, 1H), 8.49 (dd, J=2.6, 0.5 Hz, 1H), 8.32 (dd,J=8.6, 0.6 Hz, 1H), 7.73 (s, 1H), 7.68 (br dd, J=8.6, 2.7 Hz, 1H), 6.66(t, J_(HF)=72.0 Hz, 1H), 3.84 (AB quartet, upfield doublet is broadened,J_(AB)=11.4 Hz, Δν_(AB)=35 Hz, 2H), 3.23 (dd, J=12.5, 4.0 Hz, 1H),2.96-2.86 (m, 1H), 2.62 (dd, J=12.7, 2.4 Hz, 1H), 2.34-2.14 (m, 3H),2.04-1.94 (m, 2H), 1.93-1.81 (m, 1H), 1.76 (dd, J=13.5, 3.8 Hz, 1H),1.74-1.61 (m, 1H).

The absolute configuration of the more potent enantiomer 5 (see Table 2)was assigned in analogy with the work reported by C. R. Butler et al.,J. Med. Chem. 2015, 58, 2678-2702, and M. A. Brodney, J. Med. Chem.2015, 58, 3223-3252. The same rationale was used in assigning theabsolute stereochemistry of all subsequent separated pairs ofenantiomers.

Example 6N-{2-[(4a′R,8a′R)-2′-Amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-chloropyridine-2-carboxamide(6)

Step 1. Synthesis of N-{2-[(4a′R,8a′R)-2′-(benzoylamino)-4a5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-chloropyridine-2-carboxamide(C89)

Triethylamine (98 μL, 0.70 mmol) was added to a mixture of5-chloropyridine-2-carboxylic acid (44.6 mg, 0.283 mmol) in ethylacetate (5 mL). The resulting solution was treated with2,4,6-tripropyl-1,3,5,2,4,6-trioxatriphosphinane 2,4,6-trioxide (50%solution in ethyl acetate; 0.169 mL, 0.284 mmol), and the reactionmixture was heated at 65° C. for 20 minutes, whereupon P5 (100 mg, 0.177mmol) was added and stirring was continued for 16 hours at 65° C. Aftercooling to room temperature, the reaction mixture was diluted with ethylacetate (100 mL) and washed sequentially with water (2×150 mL),saturated aqueous sodium bicarbonate solution (250 mL), and saturatedaqueous sodium chloride solution (250 mL), dried over sodium sulfate,filtered, and concentrated in vacuo. The residue was dissolved indichloromethane (3 mL) and treated with trifluoroacetic acid (0.68 mL,8.8 mmol). After the reaction mixture had stirred at room temperaturefor 16 hours, dichloromethane (100 mL) was added, and the resultingsolution was treated with saturated aqueous sodium bicarbonate solution(350 mL). The organic layer was washed with saturated aqueous sodiumchloride solution (250 mL), dried over sodium sulfate, filtered, andconcentrated under reduced pressure. Chromatography on silica gel(Gradient: 0% to 100% ethyl acetate in heptane) afforded the product asa yellow solid. Yield: 61.2 mg, 0.110 mmol, 62%. ¹H NMR (400 MHz, CDCl₃)δ 10.42 (br s, 1H), 8.60 (dd, J=2.4, 0.6 Hz, 1H), 8.25 (dd, J=8.4, 0.6Hz, 1H), 8.17-8.05 (m, 2H), 7.91 (dd, J=8.3, 2.4 Hz, 1H), 7.78 (s, 1H),7.57-7.51 (m, 1H), 7.46 (br dd, J=7.7, 7.0 Hz, 2H), 3.85 (AB quartet,J_(AB)=11.9 Hz, Δν_(AB)=80.9 Hz, 2H), 3.22 (dd, J=12.9, 4.1 Hz, 1H),3.09-3.00 (m, 1H), 2.61 (dd, J=13.1, 2.7 Hz, 1H), 2.32-1.97 (m, 5H),1.95-1.82 (m, 2H), 1.77-1.64 (m, 1H).

Step 2. Synthesis ofN-{2-[(4a′R,8a′R)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-chloropyridine-2-carboxamide(6)

Conversion of C89 to 6 was carried out according to the proceduredescribed for synthesis of 3 from C88 in Examples 3, 4, and 5. In thiscase, the material obtained from the silica gel chromatographicpurification was triturated with diethyl ether (5 mL) to provide theproduct as a white solid. Yield: 26 mg, 58 μmol, 53%. LCMS m/z 450.3[M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ 10.39 (br s, 1H), 8.59 (dd, J=2.3, 0.7Hz, 1H), 8.24 (dd, J=8.3, 0.6 Hz, 1H), 7.90 (dd, J=8.4, 2.3 Hz, 1H),7.71 (s, 1H), 4.59-4.47 (br s, 2H), 3.80 (AB quartet, J_(AB)=11.2 Hz,Δν_(AB)=61.7 Hz, 2H), 3.21 (dd, J=12.6, 4.1 Hz, 1H), 2.88-2.81 (m, 1H),2.59 (dd, J=12.5, 2.7 Hz, 1H), 2.32-2.15 (m, 3H), 2.05-1.95 (m, 2H),1.92-1.81 (m, 1H), 1.74-1.60 (m, 1H), 1.73 (dd, J=13.3, 4.1 Hz, 1H).

Example 7N-{2-[(4aR,8aR)-2-Amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide(7)

Step 1. Synthesis ofN-{2-[(4aR,8aR)-2-(benzoylamino)-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide(C90)

Triethylamine (7.0 mL, 50 mmol) was added to a mixture of P19 (3.83 g,20.3 mmol) in ethyl acetate (63 mL). To the resulting solution was added2,4,6-tripropyl-1,3,5,2,4,6-trioxatriphosphinane 2,4,6-trioxide (50%solution in ethyl acetate; 30.2 mL, 50.7 mmol), and the reaction mixturewas heated at 65° C. for 20 minutes. A solution of P3 (7.0 g, 13 mmol)in ethyl acetate (25 mL) was added, and the reaction mixture was stirredat 65° C. for 1 hour. After cooling to room temperature, the reactionmixture was diluted with ethyl acetate and washed sequentially withwater (twice), saturated aqueous sodium bicarbonate solution (until theresulting aqueous wash reached a pH of 8), and saturated aqueous sodiumchloride solution. It was then dried over sodium sulfate, filtered, andconcentrated in vacuo; the resulting solid was dissolved indichloromethane (700 mL), treated with trifluoroacetic acid (49 mL, 640mmol), and allowed to stir at room temperature overnight. The reactionmixture was then diluted with dichloromethane and basified via additionof 1 M aqueous sodium hydroxide solution. The aqueous layer wasextracted twice with dichloromethane, and the combined organic layerswere washed with saturated aqueous sodium chloride solution, dried oversodium sulfate, filtered, and concentrated under reduced pressure.Silica gel chromatography (Gradient: 0% to 100% ethyl acetate inheptane) provided a residue, which was triturated for an hour in heptanecontaining a small amount of ethyl acetate. The product was obtained asa yellow solid. Yield: 3.70 g, 6.45 mmol, 50%. LCMS m/z 574.3 [M+H]⁺. ¹HNMR (400 MHz, CDCl₃), characteristic peaks: δ 12.50-12.35 (br s, 1H),10.44 (br s, 1H), 8.50 (dd, J=2.6, 0.6 Hz, 1H), 8.33 (dd, J=8.6, 0.6 Hz,1H), 7.78 (br s, 1H), 7.69 (dd, J=8.6, 2.6 Hz, 1H), 7.61-7.40 (br m,3H), 6.66 (t, J_(HF)=71.9 Hz, 1H), 4.25-4.13 (m, 1H), 3.76 (d, J=12.5Hz, 1H), 3.30-3.11 (m, 2H), 2.63-2.52 (m, 1H), 2.16-1.99 (m, 1H),1.57-1.49 (m, 1H), 1.48 (s, 3H), 1.34 (s, 3H).

Step 2. Synthesis ofN-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide(7)

A mixture of C90 (3.70 g, 6.45 mmol) and1,8-diazabicyclo[5.4.0]undec-7-ene (95%, 1.02 mL, 6.48 mmol) in methanol(104 mL) was heated to 70° C. Additional methanol (500 mL) anddichloromethane (100 mL) were added to fully solubilize the reagents,and the reaction mixture was stirred overnight at 70° C. After thereaction mixture had cooled, it was added to ethyl acetate, and themixture was washed sequentially with aqueous sodium bicarbonate solutionand saturated aqueous sodium chloride solution, dried over sodiumsulfate, filtered, and concentrated in vacuo. Silica gel chromatography(Gradient: 0% to 5% methanol in dichloromethane), followed bytrituration in heptane containing a small amount of dichloromethane,provided the product as a white solid. This material proved to becrystalline via powder X-ray diffraction. Yield: 2.15 g, 4.58 mmol, 71%.LCMS m/z 470.3 [M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ 10.40 (br s, 1H), 8.49(dd, J=2.6, 0.5 Hz, 1H), 8.32 (dd, J=8.7, 0.5 Hz, 1H), 7.71 (s, 1H),7.68 (br dd, J=8.6, 2.6 Hz, 1H), 6.66 (t, J_(HF)=71.9 Hz, 1H), 4.56 (brs, 2H), 4.10 (d, J=11.5 Hz, 1H), 3.73 (d, J=11.5 Hz, 1H), 3.21 (dd,J=12.5, 4.1 Hz, 1H), 2.98 (dddd, J=13, 4, 4, 3 Hz, 1H), 2.55 (dd,J=12.5, 2.7 Hz, 1H), 1.96 (dd, J=13.3, 13.2 Hz, 1H), 1.46 (s, 3H), 1.38(dd, J=13.4, 4.1 Hz, 1H), 1.33 (s, 3H).

Example 8N-{2-[(4aR,6S,8aR)-2-Amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide(8)

Step 1. Synthesis ofN-{2-[(4aR,6S,8aR)-2-(benzoylamino)-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)-N-(2,4-dimethoxybenzyl)pyridine-2-carboxamide(C91)

2,4,6-Tripropyl-1,3,5,2,4,6-trioxatriphosphinane 2,4,6-trioxide (50%solution in ethyl acetate, 0.25 mL, 0.42 mmol) was added to a mixture ofP19 (32.0 mg, 0.169 mmol) and triethylamine (59 μL, 0.42 mmol) in ethylacetate (0.2 mL). The reaction mixture was heated to 60° C. for 20minutes, whereupon P6 (60.0 mg, 0.106 mmol) was added, and stirring wascontinued at 60° C. for 1 hour. The reaction mixture was then dilutedwith ethyl acetate and water. The aqueous layer was extracted twice withethyl acetate, and the combined organic layers were washed twice withsaturated aqueous sodium bicarbonate solution and once with saturatedaqueous sodium chloride solution, dried over sodium sulfate, filtered,and concentrated in vacuo. LCMS m/z 738.5 [M+H]⁺. This residue wassubjected to chromatography on silica gel (Gradient: 0% to 60% ethylacetate in heptane) to afford the product (77 mg), which was takendirectly to the following step.

Step 2. Synthesis ofN-{2-[(4aR,6S,8aR)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide(8)

Trifluoroacetic acid (0.2 mL) was added to a solution of C91 (from theprevious step; 77 mg, 0.10 mmol) in dichloromethane (0.5 mL), and thereaction mixture was stirred at room temperature for 45 minutes. It wasthen concentrated under reduced pressure, and the residue waspartitioned between ethyl acetate and saturated aqueous sodiumbicarbonate solution. The aqueous layer was extracted three times withethyl acetate, and the combined organic layers were dried over sodiumsulfate, filtered, and concentrated in vacuo. The resulting material (60mg) was dissolved in ethanol (1 mL), treated with pyridine (0.16 mL) andO-benzylhydroxylamine hydrochloride (155 mg, 0.970 mmol), and heated at50° C. for 3 hours. After the reaction mixture had been concentrated invacuo, the residue was partitioned between diethyl ether and 0.25 Maqueous hydrochloric acid. The aqueous layer was washed six times withdiethyl ether, whereupon it was adjusted to a pH of approximately 12 viaslow addition of 1 M aqueous sodium hydroxide solution. The aqueouslayer was then extracted three times with dichloromethane, and thecombined dichloromethane extracts were dried over sodium sulfate,filtered, and concentrated in vacuo. Silica gel chromatography(Gradient: 0% to 50% ethyl acetate in heptane) provided the product.Yield: 17.4 mg, 36 μmol, 34% over 2 steps. LCMS m/z 484.4 [M+H]⁺. ¹H NMR(400 MHz, CDCl₃) δ 10.40 (br s, 1H), 8.49 (d, J=2.7 Hz, 1H), 8.32 (d,J=8.6 Hz, 1H), 7.70 (s, 1H), 7.68 (br dd, J=8.6, 2.7 Hz, 1H), 6.65 (t,J_(HF)=72.0 Hz, 1H), 5.0-4.2 (v br s, 2H), 4.08 (d, J=11.5 Hz, 1H), 3.71(d, J=11.5 Hz, 1H), 3.22 (dd, J=12.5, 4.2 Hz, 1H), 3.03-2.95 (m, 1H),2.55 (dd, J=12.5, 2.7 Hz, 1H), 1.91 (dd, J=13.3, 13.2 Hz, 1H), 1.68-1.51(m, 2H), 1.39 (s, 3H), 1.33 (dd, J=13.4, 4.2 Hz, 1H), 0.95 (t, J=7.5 Hz,3H).

The absolute and relative stereochemistry of 8 and its isomers inExamples 26, 27, and 28 were assigned on the basis of the stereodefinedsynthesis of 8 carried out in Alternate Synthesis of Example 8 below,NMR work, and the biological activity of these compounds. From the ¹HNMR spectra, 8 and 28 are enantiomers of one another; 26 and 27 are alsoenantiomers of one another. This information, in conjunction with thestereodefined synthesis of Example 8 below, allowed assignment of theconfiguration at the quaternary centers bearing the methyl and ethylgroups of 8 and 28. Examination of the biological activity of the fourcompounds (see Table 2), in conjunction with consideration of theremaining stereochemical possibilities, provided the absoluteconfigurations at the ring fusion and the quaternary center for 26 and27 (see discussion under Isolation of C9 and C10 in Preparation P2above).

Alternate Synthesis of Example 8N-{2-[(4aR,6S,8aR)-2-Amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide(8)

Step 1. Synthesis of di-tert-butyl{(4aR,6S,8aR)-8a-[4-({[5-(difluoromethoxy)pyridin-2-yl]carbonyl}amino)-1,3-thiazol-2-yl]-6-ethyl-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl}imidodicarbonate(C92)

A mixture of P19 (18.1 mg, 95.7 μmol), triethylamine (44.5 μL, 0.319mmol), and 2,4,6-tripropyl-1,3,5,2,4,6-trioxatriphosphinane2,4,6-trioxide (50% solution in ethyl acetate; 190 μL, 0.319 mmol) inethyl acetate (1 mL) was heated at 55° C. for 20 minutes. The reactionmixture was then allowed to cool to 45° C., whereupon P16 (41 mg, 80μmol) was added, and heating was continued at 45° C. for 1 hour. Afterthe reaction mixture had cooled to room temperature, it was partitionedbetween ethyl acetate (15 mL) and saturated aqueous sodium bicarbonatesolution (10 mL). The aqueous layer was then extracted with ethylacetate (15 mL), and the combined organic layers were dried over sodiumsulfate, filtered, and concentrated in vacuo. Chromatography on silicagel (Gradient: 0% to 90% ethyl acetate in heptane) afforded the productas a white solid. Yield: 26.4 mg, 38.6 μmol, 48%. ¹H NMR (400 MHz,CDCl₃) δ 10.41 (br s, 1H), 8.50 (br d, J=2.3 Hz, 1H), 8.32 (br d, J=8.6Hz, 1H), 7.75 (s, 1H), 7.68 (br dd, J=8.6, 2.6 Hz, 1H), 6.66 (t,J_(HF)=72.0 Hz, 1H), 3.97 (AB quartet, J_(AB)=11.7 Hz, Δν_(AB)=60.3 Hz,2H), 3.37 (dd, J=12.8, 4.0 Hz, 1H), 3.22-3.13 (m, 1H), 2.63 (dd, J=12.7,2.7 Hz, 1H), 2.05 (dd, J=13.4, 13.4 Hz, 1H), 1.68-1.54 (m, 2H), 1.54 (s,18H), 1.43-1.36 (m, 1H), 1.39 (s, 3H), 0.95 (t, J=7.5 Hz, 3H).

Step 2. Synthesis ofN-{2-[(4aR,6S,8aR)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide(8)

A mixture of C92 (26 mg, 38 μmol) and a solution of hydrogen chloride in1,4-dioxane (4 M, 1 mL) was stirred at 51° C. for 7 hours. After thereaction mixture had cooled to room temperature, it was concentrated invacuo, and the residue was treated with aqueous sodium bicarbonatesolution (5 mL) and extracted with ethyl acetate (4×7.5 mL). Thecombined organic layers were dried over sodium sulfate, filtered, andconcentrated in vacuo. Silica gel chromatography (Gradient: 0% to 100%ethyl acetate in heptane) provided the product as a white solid. Yield:15.8 mg, 32.6 μmol, 86%. LCMS m/z 484.3 [M+H]⁺. ¹H NMR (400 MHz, CDCl₃)δ 10.40 (br s, 1H), 8.49 (d, J=2.5 Hz, 1H), 8.32 (d, J=8.6 Hz, 1H), 7.71(s, 1H), 7.68 (dd, J=8.6, 2.5 Hz, 1H), 6.66 (t, J_(HF)=71.9 Hz, 1H),5.0-4.2 (v br s, 2H), 4.08 (d, J=11.5 Hz, 1H), 3.72 (d, J=11.5 Hz, 1H),3.22 (dd, J=12.5, 4.1 Hz, 1H), 3.03-2.95 (m, 1H), 2.55 (dd, J=12.5, 2.7Hz, 1H), 1.91 (dd, J=13.3, 13.3 Hz, 1H), 1.68-1.52 (m, 2H), 1.40 (s,3H), 1.34 (dd, J=13.3, 4.1 Hz, 1H), 0.95 (t, J=7.5 Hz, 3H).

Example 9N-{2-[(4aR,6R,8aR)-2-Amino-6-(methoxymethyl)-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide(9)

Step 1. Synthesis of N-[(4aR,6R,8aR)-8a-{4-[(2,4-dimethoxybenzyl)amino]-1,3-thiazol-2-yl}-6-(methoxymethyl)-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide(C93)

A mixture of tris(dibenzylideneacetone)dipalladium(0) (4.7 mg, 5.1μmol), di-tert-butyl[2′,4′,6′-tri(propan-2-yl)biphenyl-2-yl]phosphane(95%, 6.7 mg, 15 μmol), and sodium tert-butoxide (22 mg, 0.23 mmol) waspurged in three cycles of evacuation followed by argon fill. 1,4-Dioxane(1.0 mL, which had been sparged with argon) was added, and the reactionmixture was stirred at 85° C. for 10 minutes. A solution of P12 (50 mg,0.10 mmol) and 1-(2,4-dimethoxyphenyl)methanamine (27 μL, 0.18 mmol) in1,4-dioxane (1.0 mL, which had been sparged with argon) was then added,and heating was continued at 95° C. for 30 minutes. After the reactionmixture had cooled nearly to room temperature, it was poured intosaturated aqueous sodium bicarbonate solution (7 mL) and extracted withethyl acetate (3×7 mL). The combined organic layers were dried oversodium sulfate, filtered, and concentrated in vacuo; silica gelchromatography (Gradient: 10% to 100% ethyl acetate in heptane) providedthe product as a light orange-white solid. Yield: 37.8 mg, 64.8 μmol,65%. ¹H NMR (400 MHz, CDCl₃) δ 8.31-8.07 (br s, 2H), 7.55-7.48 (m, 1H),7.48-7.41 (m, 2H), 7.21 (d, J=8.2 Hz, 1H), 6.48 (d, half of AB quartet,J=2.3 Hz, 1H), 6.45 (dd, half of ABX pattern, J=8.2, 2.4 Hz, 1H), 5.73(s, 1H), 4.68 (br t, J=6 Hz, 1H), 4.24-4.15 (m, 3H), 3.85 (s, 3H), 3.81(s, 3H), 3.73 (d, J=12.5 Hz, 1H), 3.38 (s, 3H), 3.32 (AB quartet,J_(AB)=9.4 Hz, Δν_(AB)=27.4 Hz, 2H), 3.31-3.24 (m, 1H), 3.24-3.15 (m,1H), 2.54 (dd, J=12.9, 2.5 Hz, 1H), 2.11-2.00 (m, 1H), 1.51-1.44 (m,1H), 1.46 (s, 3H).

Step 2. Synthesis ofN-{2-[(4aR,6R,8aR)-2-(benzoylamino)-6-(methoxymethyl)-6-methyl-4, 4a, 5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)-N-(2,4-dimethoxybenzyl)pyridine-2-carboxamide(C94)

Conversion of C93 to C94 was effected using the method described forsynthesis of C87 from P4 in Examples 3, 4 and 5. The product wasisolated as a yellow-orange-white solid. Yield: 27 mg, 36 μmol, 57%.LCMS m/z 754.5 [M+H]⁺. ¹H NMR (400 MHz, CDCl₃), characteristic peaks: δ7.80 (d, J=8.5 Hz, 1H), 7.57-7.49 (m, 2H), 7.45 (br dd, J=8, 7 Hz, 2H),6.57 (t, J_(HF)=71.9 Hz, 1H), 6.47-6.35 (m, 2H), 5.28-5.03 (m, 2H), 3.78(s, 3H), 3.70 (s, 3H), 3.63-3.53 (m, 1H), 3.37 (s, 3H), 3.28 (ABquartet, J_(AB)=9.4 Hz, Δν_(AB)=22.3 Hz, 2H), 2.95-2.73 (m, 2H), 2.43(dd, J=12.9, 2.4 Hz, 1H), 1.97 (dd, J=13, 13 Hz, 1H), 1.44-1.36 (m, 1H),1.35 (br s, 3H).

Step 3. Synthesis ofN-{2-[(4aR,6R,8aR)-2-(benzoylamino)-6-(methoxymethyl)-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide(C95)

A mixture of C94 (27 mg, 36 μmol), dichloromethane (250 μL), andtrifluoroacetic acid (69 μL, 0.90 mmol) was stirred at room temperaturefor 2.5 hours, whereupon the reaction mixture was concentrated underreduced pressure, diluted with saturated aqueous sodium bicarbonatesolution (4 mL), and extracted with ethyl acetate (4×5 mL). The combinedorganic layers were dried over sodium sulfate, filtered, andconcentrated in vacuo, providing a residue (23 mg) that was takendirectly to the following step. LCMS m/z 604.5 [M+H]⁺. ¹H NMR (400 MHz,CDCl₃), characteristic peaks: δ 8.46 (d, J=2.5 Hz, 1H), 8.25 (d, J=8.6Hz, 1H), 8.03 (br d, J=7.6 Hz, 2H), 7.71 (s, 1H), 7.65 (dd, J=8.7, 2.6Hz, 1H), 7.56-7.48 (m, 1H), 7.44 (br dd, J=8, 7 Hz, 2H), 6.66 (t,J_(HF)=72.0 Hz, 1H), 4.14 (d, J=11.9 Hz, 1H), 3.35 (s, 3H), 3.29 (ABquartet, J_(AB)=9.6 Hz, Δν_(AB)=18.3 Hz, 2H), 2.05-1.94 (m, 1H),1.50-1.41 (m, 1H), 1.45 (s, 3H).

Step 4. Synthesis ofN-{2-[(4aR,6R,8aR)-2-amino-6-(methoxymethyl)-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide(9)

A solution of C95 (from the previous step; 23 mg, ≦36 μmol) andmethylamine (33% solution in ethanol; 0.4 mL) in ethanol (0.4 mL) wasstirred at room temperature overnight. Removal of solvent in vacuoprovided a solid, which was subjected to chromatography on silica gel(Gradient: 20% to 100% ethyl acetate in heptane). The product wasisolated as a white solid. Yield: 14 mg, 28 μmol, 78% over 2 steps. LCMSm/z 500.4 [M+H]⁺. ¹H NMR (400 MHz, CDCl₃) δ 10.40 (br s, 1H), 8.49 (d,J=2.5 Hz, 1H), 8.32 (d, J=8.7 Hz, 1H), 7.71 (s, 1H), 7.68 (dd, J=8.6,2.6 Hz, 1H), 6.65 (t, J_(HF)=72.0 Hz, 1H), 4.11 (d, J=11.5 Hz, 1H), 3.76(d, J=11.5 Hz, 1H), 3.42 (s, 3H), 3.34 (AB quartet, J_(AB)=9.3 Hz,Δν_(AB)=18.4 Hz, 2H), 3.22 (dd, J=12.5, 4.1 Hz, 1H), 3.06-2.98 (m, 1H),2.57 (dd, J=12.5, 2.7 Hz, 1H), 1.98 (dd, J=13.4, 13.3 Hz, 1H), 1.49 (s,3H), 1.38 (dd, J=13.4, 4.1 Hz, 1H).

Example 10N-{2-[(4aR,8aR)-2-Amino-6,6-bis(fluoromethyl)-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide(10)

Step 1. Synthesis of di-tert-butyl[(4aR,8aR)-8a-[4-({[5-(difluoromethoxy)pyridin-2-yl]carbonyl}amino)-1,3-thiazol-2-yl]-6,6-bis(fluoromethyl)-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]imidodicarbonate(C96)

A mixture of P19 (2.48 mg, 13.1 μmol), N,N-diisopropylethylamine (4.3 μL25 μmol), and 2-[2-oxo-1(2H)-pyridyl]-1,1,3,3-tetramethyluroniumtetrafluoroborate (TPTU; 4.28 mg, 14.4 μmol) in N,N-dimethylformamide(100 μL) was stirred for 20 minutes, whereupon additional TPTU (0.1equivalent) was added. After another 10 minutes, a solution of P15 (7mg, 0.01 mmol) in N,N-dimethylformamide (114 μL) was added in oneportion to the reaction mixture, and stirring was continued for 24hours. Aqueous sodium bicarbonate solution and ethyl acetate were thenadded, and the aqueous layer was extracted twice with ethyl acetate. Thecombined organic layers were washed with saturated aqueous sodiumchloride solution, dried over sodium sulfate, filtered, and concentratedin vacuo; silica gel chromatography was carried out twice (Column #1gradient: 0% to 100% ethyl acetate in heptane; Column #2 gradient: 0% to50% ethyl acetate in heptane) to provide the product. Yield: 2 mg, 3μmol, 30%. ¹H NMR (400 MHz, CDCl₃) δ 10.43 (br s, 1H), 8.50 (d, J=2.4Hz, 1H), 8.32 (d, J=8.6 Hz, 1H), 7.78 (s, 1H), 7.69 (dd, J=8.6, 2.5 Hz,1H), 6.66 (t, J_(HF)=72.0 Hz, 1H), 4.98-4.72 (m, 2H), 4.55-4.27 (m, 2H),4.05 (AB quartet, J_(AB)=11.7 Hz, Δν_(AB)=49.3 Hz, 2H), 3.35 (dd,J=13.0, 3.9 Hz, 1H), 3.25-3.15 (m, 1H), 2.70 (dd, J=12.9, 2.7 Hz, 1H),2.21-2.09 (m, 1H), 1.75-1.67 (m, 1H), 1.55 (s, 18H).

Step 2. Synthesis ofN-{2-[(4aR,8aR)-2-amino-6,6-bis(fluoromethyl)-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide(10)

Trifluoroacetic acid (0.1 mL) was added drop-wise to a 0° C. solution ofC96 (2 mg, 3 μmol) in dichloromethane (0.4 mL). The cooling bath wasremoved, and the reaction mixture was stirred for 1.25 hours, whereupon10% aqueous sodium bicarbonate solution and dichloromethane were added.The aqueous layer was extracted with dichloromethane (3×25 mL), and thecombined organic layers were washed with saturated aqueous sodiumchloride solution, dried over sodium sulfate, filtered, and concentratedin vacuo. Silica gel chromatography (Gradient: 0% to 10% methanol indichloromethane) provided the product. Yield: 0.5 mg, 0.9 μmol, 30%.LCMS m/z 506.3 [M+H]⁺. ¹H NMR (400 MHz, CDCl₃), characteristic peaks: δ10.43 (br s, 1H), 8.50 (d, J=2.4 Hz, 1H), 8.32 (br d, J=8.6 Hz, 1H),7.72-7.66 (m, 1H), 6.67 (t, J_(HF)=71.9 Hz, 1H), 4.98-4.71 (m, 2H),4.52-4.23 (m, 3H), 3.34 (dd, J=13, 4 Hz, 1H), 2.79 (br d, J=13 Hz, 1H).

TABLE 1 Method of Preparation, Structure, and Physicochemical Propertiesfor Examples 11-41. Method of Preparation; Non- commercial ¹H NMR (400MHz, CHCl₃) δ; Mass Example starting spectrum, observed ion m/z [M + H]⁺Number materials Structure (unless otherwise indicated) 11 Examples 1and 2^(1,2); P1

9.36 (br s, 1H), 7.90 (d, J = 2.5 Hz, 1H), 7.64 (s, 1H), 7.24 (t, J_(HF)= 60.2 Hz, 1H), 7.08 (d, J = 2.4 Hz, 1H), 4.75- 4.52 (br s, 2H), 4.07(d, J = 11.5 Hz, 1H), 3.71 (d, J = 11.5 Hz, 1H), 3.19 (dd, J = 12.6, 3.8Hz, 1H), 2.98-2.89 (m, 1H), 2.54 (br dd, J = 12.4, 2 Hz, 1H), 1.95 (dd,J = 13.2, 13.2 Hz, 1H), 1.44 (s, 3H), 1.37 (dd, J = 13.6, 3.8 Hz, 1H),1.32 (s, 3H); 442.9 12 Examples 1 and 2^(1,2); P1

9.36 (br s, 1H), 7.90 (d, J = 2.5 Hz, 1H), 7.64 (s, 1H), 7.24 (t, J_(HF)= 60.2 Hz, 1H), 7.08 (d, J = 2.6 Hz, 1H), 4.75- 4.51 (br s, 2H), 4.07(d, J = 11.4 Hz, 1H), 3.72 (d, J = 11.4 Hz, 1H), 3.19 (dd, J = 12.4, 4.1Hz, 1H), 2.99-2.90 (m, 1H), 2.54 (br dd, J = 12.4, 2 Hz, 1H), 1.96 (dd,J = 13.3, 13.2 Hz, 1H), 1.44 (s, 3H), 1.38 (dd, J = 13.3, 3.9 Hz, 1H),1.32 (s, 3H); 442.9 13 Examples 1 and 2^(3,4); P1

10.11 (s, 1H), 9.08 (s, 1H), 8.37 (s, 1H), 7.72 (s, 1H), 7.52 (t, J_(HF)= 71.5 Hz, 1H), 4.08 (d, J = 11 Hz, 1H), 3.72 (d, J = 11 Hz, 1H), 3.19(d, J = 11 Hz, 1H), 3.02-2.89 (m, 1H), 2.55 (d, J = 11 Hz, 1H), 1.96(dd, J = 13, 13 Hz, 1H), 1.45 (s, 3H), 1.43-1.34 (m, 1H), 1.33 (s, 3H);470.9 14 Examples 1 and 2^(3,4); P1

10.11 (s, 1H), 9.07 (s, 1H), 8.37 (s, 1H), 7.71 (s, 1H), 7.52 (t, J_(HF)= 71.4 Hz, 1H), 4.08 (d, J = 11.5 Hz, 1H), 3.72 (d, J = 11.5 Hz, 1H),3.19 (dd, J = 12.6, 3.9 Hz, 1H), 3.01-2.90 (m, 1H), 2.55 (br d, J = 12.4Hz, 1H), 1.96 (dd, J = 13.4, 13.3 Hz, 1H), 1.45 (s, 3H), 1.38 (dd, J =13.4, 3.8 Hz, 1H), 1.32 (s, 3H); 470.9 15 Examples 1 and 2⁵; P1, P19

10.40 (br s, 1H), 8.49 (br s, 1H), 8.32 (d, J = 8.8 Hz, 1H), 7.73-7.64(m, 1H), 7.70 (s, 1H), 6.66 (t, J_(HF) = 71.9 Hz, 1H), 4.90-4.35 (br s,2H), 4.09 (d, J = 11.5 Hz, 1H), 3.72 (d, J = 11.5 Hz, 1H), 3.20 (dd, J =12.4, 3.6 Hz, 1H), 3.03-2.92 (m, 1H), 2.54 (br d, J = 12.3 Hz, 1H), 1.96(dd, J = 13.6, 13.0 Hz, 1H), 1.45 (s, 3H), 1.38 (dd, J = 13, 4 Hz, 1H),1.32 (s, 3H); 469.9 16 Examples 1 and 2^(6,7); P1

10.43 (s, 1H), 8.49 (s, 1H), 8.28 (d, J = 8 Hz, 1H), 7.79-7.64 (m, 2H),4.85- 4.43 (br s, 2H), 4.09 (d, J = 11 Hz, 1H), 3.72 (d, J = 11 Hz, 1H),3.20 (br d, J = 11 Hz, 1H), 3.04-2.90 (m, 1H), 2.54 (d, J = 12 Hz, 1H),2.12-1.89 (m, 4H), 1.46 (s, 3H), 1.42-1.33 (m, 1H), 1.32 (s, 3H); 483.917 Examples 1 and 2^(6,7); P1

10.43 (s, 1H), 8.49 (s, 1H), 8.28 (d, J = 8.5 Hz, 1H), 7.78-7.66 (m,2H), 5.0- 4.3 (br s, 2H), 4.09 (d, J = 11 Hz, 1H), 3.72 (d, J = 11 Hz,1H), 3.20 (br d, J = 12 Hz, 1H), 3.03-2.92 (m, 1H), 2.54 (d, J = 12 Hz,1H), 2.09-1.89 (m, 4H), 1.45 (s, 3H), 1.42-1.34 (m, 1H), 1.32 (s, 3H);483.9 18 Examples 1 and 2^(1,8,9); P1

10.12 (s, 1H), 9.02 (s, 1H), 8.30 (s, 1H), 7.70 (s, 1H), 4.80-4.42 (brs, 2H), 4.62 (t, J_(HF) = 11.9 Hz, 2H), 4.09 (d, J = 11.8 Hz, 1H), 3.73(d, J = 11.8 Hz, 1H), 3.20 (br d, J = 12 Hz, 1H), 3.01- 2.92 (m, 1H),2.55 (br d, J = 12 Hz, 1H), 1.96 (dd, J = 13, 13 Hz, 1H), 1.79 (t,J_(HF) = 18.7 Hz, 3H), 1.45 (s, 3H), 1.38 (br d, J = 13 Hz, 1H), 1.33(s, 3H); 499.0 19 Examples 1 and 2^(1,8,9); P1

10.12 (s, 1H), 9.01 (s, 1H), 8.30 (s, 1H), 7.70 (s, 1H), 4.8-4.5 (br s,2H), 4.62 (t, J_(HF) = 11.9 Hz, 2H), 4.08 (d, J = 11.3 Hz, 1H), 3.73 (d,J = 11.5 Hz, 1H), 3.20 (dd, J = 12, 3 Hz, 1H), 3.02- 2.92 (m, 1H), 2.55(br d, J = 12 Hz, 1H), 1.96 (dd, J = 13, 13 Hz, 1H), 1.79 (t, J_(HF) =18.6 Hz, 3H), 1.45 (s, 3H), 1.38 (dd, J = 13, 3 Hz, 1H), 1.33 (s, 3H);499.0 20 Examples 1 and 2^(1,10,11); P1

10.12 (s, 1H), 9.03 (s, 1H), 8.23 (s, 1H), 7.70 (s, 1H), 5.08-5.04 (m,2H), 4.09 (d, J = 11.4 Hz, 1H), 3.73 (d, J = 11.4 Hz, 1H), 3.20 (dd, J =12, 4 Hz, 1H), 3.00-2.92 (m, 1H), 2.54 (br d, J = 12 Hz, 1H), 1.96 (dd,J = 13, 13 Hz, 1H), 1.92-1.88 (m, 3H), 1.45 (s, 3H), 1.38 (dd, J = 13,3.5 Hz, 1H), 1.33 (s, 3H); 472.9 21 Examples 1 and 2^(1,10,11); P1

10.12 (s, 1H), 9.02 (s, 1H), 8.23 (s, 1H), 7.69 (s, 1H), 5.06 (s, 2H),4.08 (d, J = 12 Hz, 1H), 3.76 (br d, J = 12 Hz, 1H), 3.20 (dd, J = 12, 4Hz, 1H), 3.03- 2.93 (m, 1H), 2.55 (br d, J = 13 Hz, 1H), 1.96 (dd, J =13, 13 Hz, 1H), 1.90 (br s, 3H), 1.45 (s, 3H), 1.42-1.35 (m, 1H), 1.33(s, 3H); 472.9 22 Examples 1 and 2^(1,12); P1, P22

9.39 (br s, 1H), 8.37 (d, J = 1.3 Hz, 1H), 7.63 (s, 1H), 5.45 (d, J_(HF)= 47.1 Hz, 2H), 4.77-4.55 (br s, 2H), 4.06 (d, J = 11.6 Hz, 1H), 3.70(d, J = 11.5 Hz, 1H), 3.18 (dd, J = 12.5, 4.1 Hz, 1H), 2.98-2.90 (m,1H), 2.54 (dd, J = 12.5, 2.6 Hz, 1H), 1.95 (dd, J = 13.4, 13.4 Hz, 1H),1.44 (s, 3H), 1.38 (dd, J = 13.4, 4.0 Hz, 1H), 1.32 (s, 3H); 425.9 23Examples 1 and 2^(1,12); P1, P22

9.39 (br s, 1H), 8.37 (d, J = 1.4 Hz, 1H), 7.63 (s, 1H), 5.45 (d, J_(HF)= 47.2 Hz, 2H), 4.78-4.59 (br s, 2H), 4.06 (d, J = 11.6 Hz, 1H), 3.70(d, J = 11.5 Hz, 1H), 3.17 (dd, J = 12.5, 4.1 Hz, 1H), 2.97-2.89 (m,1H), 2.54 (dd, J = 12.6, 2.8 Hz, 1H), 1.95 (dd, J = 13.4, 13.2 Hz, 1H),1.44 (s, 3H), 1.37 (dd, J = 13.3, 4.1 Hz, 1H), 1.32 (s, 3H); 425.9 24Example 7; P3, P20

10.57 (br s, 1H), 8.35 (br d, J = 2.6 Hz, 1H), 7.67 (s, 1H), 7.43-7.41(m, 1H), 6.63 (t, J_(HF) = 72.2 Hz, 1H), 4.58-4.50 (br s, 2H), 4.10 (d,J = 11.5 Hz, 1H), 3.72 (d, J = 11.5 Hz, 1H), 3.21 (dd, J = 12.5, 4.1 Hz,1H), 3.02-2.94 (m, 1H), 2.84 (s, 3H), 2.54 (dd, J = 12.5, 2.6 Hz, 1H),1.96 (dd, J = 13.3, 13.3 Hz, 1H), 1.46 (s, 3H), 1.38 (dd, J = 13.4, 4.0Hz, 1H), 1.33 (s, 3H); 484.3 25 Examples 1 and 2¹³; P1, P20

10.58 (br s, 1H), 8.37-8.33 (m, 1H), 7.67 (s, 1H), 7.45-7.40 (m, 1H),6.64 (t, J_(HF) = 72.1 Hz, 1H), 4.87-4.40 (v br s, 2H), 4.10 (d, J =11.5 Hz, 1H), 3.73 (d, J = 11.5 Hz, 1H), 3.21 (dd, J = 12.4, 4.0 Hz,1H), 3.02-2.94 (m, 1H), 2.84 (s, 3H), 2.58-2.51 (m, 1H), 1.96 (dd, J =13.3, 13.2 Hz, 1H), 1.46 (s, 3H), 1.38 (dd, J = 13.5, 4 Hz, 1H), 1.33(s, 3H); 484.0 26 Example 8; P7, P19

10.39 (br s, 1H), 8.49 (d, J = 2.7 Hz, 1H), 8.32 (d, J = 8.6 Hz, 1H),7.70 (s, 1H), 7.68 (br dd, J = 8.6, 2.7 Hz, 1H), 6.66 (t, J_(HF) = 72.0Hz, 1H), 4.91-4.42 (br s, 2H), 3.98 (d, J = 11.5 Hz, 1H), 3.67 (d, J =11.5 Hz, 1H), 3.19 (dd, J = 12.5, 4.1 Hz, 1H), 3.00-2.92 (m, 1H), 2.53(dd, J = 12.5, 2.7 Hz, 1H), 2.19-2.07 (m, 1H), 1.93 (dd, J = 13.4, 13.4Hz, 1H), 1.66-1.55 (m, 1H), 1.44 (dd, J = 13.6, 4.1 Hz, 1H), 1.23 (s,3H), 0.95 (t, J = 7.4 Hz, 3H); 484.4 27 Example 8; P8, P19

10.40 (br s, 1H), 8.49 (br d, J = 2.6 Hz, 1H), 8.32 (d, J = 8.6 Hz, 1H),7.70 (s, 1H), 7.68 (br dd, J = 8.6, 2.7 Hz, 1H), 6.66 (t, J_(HF) = 72.0Hz, 1H), 4.85-4.50 (br s, 2H), 3.98 (d, J = 11.5 Hz, 1H), 3.67 (d, J =11.5 Hz, 1H), 3.19 (dd, J = 12.5, 4.1 Hz, 1H), 3.00-2.92 (m, 1H), 2.53(dd, J = 12.5, 2.7 Hz, 1H), 2.19-2.07 (m, 1H), 1.93 (dd, J = 13.4, 13.4Hz, 1H), 1.66-1.55 (m, 1H), 1.44 (dd, J = 13.6, 4.1 Hz, 1H), 1.23 (s,3H), 0.95 (t, J = 7.4 Hz, 3H); 484.2 28 Example 8; P9, P19

Somewhat impure; characteristic product peaks: 10.41 (br s, 1H), 8.50(d, J = 2.8 Hz, 1H), 8.32 (d, J = 8.7 Hz, 1H), 7.76 (s, 1H), 6.66 (t,J_(HF) = 72.0 Hz, 1H), 4.10 (d, J = 12.1 Hz, 1H), 3.88 (br d, J = 12 Hz,1H), 3.26 (dd, J = 12.4, 4.2 Hz, 1H), 2.62 (dd, J = 12.6, 2.6 Hz, 1H),1.90 (dd, J = 13, 13 Hz, 1H), 1.67- 1.56 (m, 2H), 1.40 (s, 3H), 1.39(dd, J = 13, 4 Hz, 1H), 0.96 (t, J = 7.6 Hz, 3H); 484.4 29 Example 8;P11, P19

10.38 (br s, 1H), 8.48 (dd, J = 2.7, 0.5 Hz, 1H), 8.32 (dd, J = 8.6, 0.6Hz, 1H), 7.72 (s, 1H), 7.68 (br dd, J = 8.6, 2.7 Hz, 1H), 6.66 (t,J_(HF) = 71.9 Hz, 1H), 4.87 (br d, J = 6.2 Hz, 1H), 4.73 (d, J = 6.6 Hz,1H), 4.68 (d, J = 6.4 Hz, 1H), 4.44 (d, J = 6.6 Hz, 1H), 3.84 (ABquartet, J_(AB) = 11.5 Hz, Δν_(AB) = 20.6 Hz, 2H), 3.21 (dd, J = 12.6,4.1 Hz, 1H), 2.86-2.79 (m, 1H), 2.65 (dd, J = 12.7, 2.7 Hz, 1H),2.25-2.16 (m, 1H), 2.10 (dd, half of ABX pattern, J = 13.6, 4.3 Hz, 1H);484.2 30 Examples 1 and 2; P2, P21

10.35 (br s, 1H), 8.44 (d, J = 2.4 Hz, 1H), 7.73 (s, 1H), 7.70 (d, J =2.4 Hz, 1H), 6.67 (t, J_(HF) = 71.3 Hz, 1H), 4.09 (d, J = 11.5 Hz, 1H),3.73 (d, J = 11.4 Hz, 1H), 3.20 (dd, J = 12.5, 4.1 Hz, 1H), 3.00-2.92(m, 1H), 2.54 (dd, J = 12.6, 2.6 Hz, 1H), 1.96 (dd, J = 13.4, 13.3 Hz,1H), 1.45 (s, 3H), 1.38 (dd, J = 13.4, 4.0 Hz, 1H), 1.32 (s, 3H); 504.1(chlorine isotope pattern observed) 31 Examples 1 and 2; P2

8.85 (br s, 1H), 7.54 (s, 1H), 4.90-4.43 (br s, 2H), 4.04 (d, J = 11 Hz,1H), 3.69 (d, J = 11 Hz, 1H), 3.17 (d, J = 11 Hz, 1H), 2.99-2.83 (m,1H), 2.53 (d, J = 12 Hz, 1H), 1.94 (dd, J = 12.5, 12.5 Hz, 1H), 1.67 (d,J_(HF) = 22.1 Hz, 6H), 1.43 (s, 3H), 1.4-1.3 (m, 1H), 1.31 (s, 3H);387.0 32 Examples 1 and 2; P2

9.18 (br s, 1H), 7.54 (s, 1H), 4.06 (d, J = 11.5 Hz, 1H), 3.70 (d, J =11.8 Hz, 1H), 3.38 (s, 3H), 3.18 (dd, J = 12.4, 4.1 Hz, 1H), 2.97-2.89(m, 1H), 2.53 (dd, J = 12.4, 2.4 Hz, 1H), 1.95 (dd, J = 13.3, 13.3 Hz,1H), 1.48 (s, 6H), 1.44 (s, 3H), 1.37 (dd, J = 13.2, 3.9 Hz, 1H), 1.32(s, 3H); 399.0 33 Examples 1 and 2; P2

7.99 (br s, 1H), 7.53 (s, 1H), 4.03 (d, J = 11.8 Hz, 1H), 3.72 (d, J =11.8 Hz, 1H), 3.16 (dd, J = 12, 4 Hz, 1H), 2.95- 2.86 (m, 1H), 2.57-2.51(m, 1H), 2.55 (s, 1H), 2.17 (s, 6H), 1.94 (dd, J = 13, 13 Hz, 1H), 1.43(s, 3H), 1.37 (dd, J = 13, 4 Hz, 1H), 1.32 (s, 3H); 393.0 34 Example 9;P13, P19

10.39 (br s, 1H), 8.49 (d, J = 2.2 Hz, 1H), 8.31 (d, J = 8.6 Hz, 1H),7.71 (s, 1H), 7.68 (dd, J = 8.6, 2.2 Hz, 1H), 6.66 (t, J_(HF) = 72.0 Hz,1H), 4.96-4.38 (v br s, 2H), 4.68 (d of AB quartets, J_(HF) = 47 Hz,J_(AB) = 9.6 Hz, Δν_(AB) = 10 Hz, 2H), 4.14 (d, J = 11.9 Hz, 1H), 3.77(d, J = 11.5 Hz, 1H), 3.20 (dd, J = 12.6, 4.0 Hz, 1H), 3.05-2.96 (m,1H), 2.58 (dd, J = 12.6, 2.2 Hz, 1H), 1.98 (ddd, J = 13.7, 13.7, 3.1 Hz,1H), 1.66 (dd, J = 14, 4 Hz, 1H), 1.32 (br s, 3H); 488.3 35 Alternatesynthesis of Example 8¹⁴; P14, P19

10.40 (br s, 1H), 8.49 (br s, 1H), 8.32 (d, J = 8.5 Hz, 1H), 7.72 (s,1H), 7.68 (br d, J = 8.6 Hz, 1H), 6.66 (t, J_(HF) = 71.9 Hz, 1H),4.9-4.4 (v br s, 2H), 4.27 (d of AB quartets, J_(HF) = 47.5 Hz, J_(AB) =9 Hz, Δν_(AB) = 10.5 Hz, 2H), 4.11 (d, J = 11.6 Hz, 1H), 3.78 (d, J =11.4 Hz, 1H), 3.23 (dd, J = 12.6, 3.9 Hz, 1H), 3.08-2.99 (m, 1H), 2.58(br d, J = 12.6 Hz, 1H), 2.03 (dd, J = 13, 13 Hz, 1H), 1.51 (br s, 3H),1.42-1.34 (m, 1H); 488.3 36 Alternate synthesis of Example 8; P16, P20

10.57 (br s, 1H), 8.36-8.33 (m, 1H), 7.67 (s, 1H), 7.43-7.40 (m, 1H),6.63 (t, J_(HF) = 72.2 Hz, 1H), 4.80-4.35 (v br s, 2H), 4.08 (d, J =11.5 Hz, 1H), 3.72 (d, J = 11.5 Hz, 1H), 3.22 (dd, J = 12.2, 4.0 Hz,1H), 3.03-2.95 (m, 1H), 2.84 (s, 3H), 2.55 (dd, J = 12.5, 2.5 Hz, 1H),1.90 (dd, J = 13.3, 13.3 Hz, 1H), 1.68- 1.51 (m, 2H), 1.39 (s, 3H), 1.33(dd, J = 13.3, 4.1 Hz, 1H), 0.95 (t, J = 7.4 Hz, 3H); 498.4 37 Alternatesynthesis of Example 8; P16

7.96 (br s, 1H), 7.52 (s, 1H), 4.80-4.27 (v br s, 2H), 4.02 (d, J = 11.5Hz, 1H), 3.68 (d, J = 11.4 Hz, 1H), 3.17 (dd, J = 12.4, 4.1 Hz, 1H),2.94-2.86 (m, 1H), 2.55 (s, 1H), 2.53 (dd, J = 12.4, 2.6 Hz, 1H), 2.18(s, 6H), 1.89 (dd, J = 13.3, 13.3 Hz, 1H), 1.67-1.50 (m, 2H), 1.37 (s,3H), 1.32 (dd, J = 13.3, 4.2 Hz, 1H), 0.94 (t, J = 7.5 Hz, 3H); 407.4 38Examples 3, 4, and 5¹⁵; P17, P19

10.42 (br s, 1H), 8.48 (br d, J = 2.7 Hz, 1H), 8.32 (br d, J = 8.6 Hz,1H), 7.73 (s, 1H), 7.68 (dd, J = 8.6, 2.6 Hz, 1H), 6.66 (t, J_(HF) =72.0 Hz, 1H), 4.63-4.49 (br s, 2H), 3.90 (AB quartet, J_(AB) = 10.8 Hz,Δν_(AB) = 50.6 Hz, 2H), 3.21 (dd, J = 12.6, 4.0 Hz, 1H), 3.05-2.97 (m,1H), 2.72-2.63 (m, 1H), 2.61 (dd, J = 12.6, 2.7 Hz, 1H), 1.04-0.95 (m,2H), 0.88-0.81 (m, 1H), 0.66-0.58 (m, 1H), 0.56-0.49 (m, 1H); 468.3¹⁶ 39Examples 3, 4, and 5¹⁵; P17, P19

10.42 (br s, 1H), 8.48 (br d, J = 2.5 Hz, 1H), 8.32 (br d, J = 8.6 Hz,1H), 7.73 (s, 1H), 7.68 (br dd, J = 8.6, 2.7 Hz, 1H), 6.66 (t, J_(HF) =71.9 Hz, 1H), 4.66- 4.50 (br s, 2H), 3.90 (AB quartet, J_(AB) = 10.7 Hz,Δν_(AB) = 50.6 Hz, 2H), 3.21 (dd, J = 12.6, 4.1 Hz, 1H), 3.04-2.97 (m,1H), 2.72-2.63 (m, 1H), 2.60 (dd, J = 12.6, 2.8 Hz, 1H), 1.04-0.95 (m,2H), 0.89-0.80 (m, 1H), 0.66-0.57 (m, 1H), 0.56-0.49 (m, 1H); 468.3¹⁶ 40Example 9; P18, P19

10.40 (br s, 1H), 8.50 (br d, J = 2.3 Hz, 1H), 8.33 (br d, J = 8.6 Hz,1H), 7.71 (s, 1H), 7.68 (br dd, J = 8.6, 2.6 Hz, 1H), 6.66 (t, J_(HF) =71.9 Hz, 1H), 4.77- 4.45 (br s, 2H), 4.11 (d, J = 11.6 Hz, 1H), 3.75 (d,J = 11.6 Hz, 1H), 3.68 (s, 2H), 3.49 (s, 3H), 3.19 (dd, J = 12.5, 4.1Hz, 1H), 3.01-2.93 (m, 1H), 2.57 (dd, J = 12.6, 2.6 Hz, 1H), 1.89 (dd, J= 13.6, 13.6 Hz, 1H), 1.62 (dd, J = 13.8, 4.2 Hz, 1H), 1.31 (s, 3H);500.4 41 Example 6; P5

10.37 (br s, 1H), 8.49 (d, J = 2.7 Hz, 1H), 8.33 (dd, J = 8.7, 4.6 Hz,1H), 7.71 (s, 1H), 7.61 (ddd, J = 8.6, 8.1, 2.8 Hz, 1H), 4.76-4.35 (brs, 2H), 3.80 (AB quartet, upfield doublet is broadened, J_(AB) = 11.3Hz, Δν_(AB) = 57,1 Hz, 2H), 3.21 (dd, J = 12.6, 4.1 Hz, 1H), 2.90-2.81(m, 1H), 2.59 (dd, J = 12.6, 2.7 Hz, 1H), 2.32-2.14 (m, 3H), 2.05-1.95(m, 2H), 1.92-1.81 (m, 1H), 1.74 (dd, J = 13.3, 4.0 Hz, 1H), 1.74-1.63(m, 1H); 434.3

1. In this case, the final deprotection was carried out using hydrazinemonohydrate, rather than methoxylamine hydrochloride.

2. Examples 11 and 12 were isolated from the corresponding racemicmaterial via supercritical fluid chromatography [Column: ChiralTechnologies Chiralpak AD, 10 μm; Mobile phase: 7:3 carbondioxide/(ethanol containing 0.1% ammonium hydroxide)]. The individualenantiomers were then purified using reversed phase HPLC (Column:Phenomenex Gemini C18, 10 μm; Mobile phase A: aqueous ammonia, pH 10;Mobile phase B: acetonitrile; Gradient: 26% to 46% B). The first-elutingenantiomer from the supercritical fluid chromatography was Example 11;the later-eluting enantiomer was Example 12. The absolute configurationof the more potent enantiomer (see Table 2), for this and all subsequentseparated pairs of enantiomers, was assigned in analogy with the workreported by C. R. Butler et al., J. Med. Chem. 2015, 58, 2678-2702, andM. A. Brodney, J. Med. Chem. 2015, 58, 3223-3252.

3. The requisite 5-(difluoromethoxy)pyrazine-2-carboxylic acid wassynthesized from methyl 5-hydroxypyrazine-2-carboxylate using thegeneral procedure described for conversion of C71 to P20 in PreparationP20.

4. Examples 13 and 14 were isolated from the corresponding racemicmaterial via supercritical fluid chromatography [Column: ChiralTechnologies Chiralpak AD, 10 μm; Mobile phase: 65:35 carbondioxide/(methanol containing 0.1% ammonium hydroxide)]. Thefirst-eluting enantiomer from the supercritical fluid chromatography wasExample 13; the later-eluting enantiomer was Example 14.

5. Example 15 was isolated from the corresponding racemic material viasupercritical fluid chromatography [Column: Chiral TechnologiesChiralpak AD, 10 μm; Mobile phase: 65:35 carbon dioxide/(methanolcontaining 0.1% ammonium hydroxide)]. Example 15 was the first-elutingenantiomer; the second-eluting enantiomer was identical to Example 7.

6. Potassium hydroxide-mediated reaction of5-hydroxypyridine-2-carbonitrile with 2-bromo-1,1-difluoroetheneprovided 5-(2-bromo-1,1-difluoroethoxy)pyridine-2-carbonitrile, whichwas subjected to the action of hydrogen chloride in methanol to affordmethyl 5-(2-bromo-1,1-difluoroethoxy)pyridine-2-carboxylate. Reductiveremoval of the bromide was effected via hydrogenation over palladium oncarbon; subsequent ester hydrolysis with lithium hydroxide provided therequisite 5-(1,1-difluoroethoxy)pyridine-2-carboxylic acid.

7. Examples 16 and 17 were isolated from the corresponding racemicmaterial via supercritical fluid chromatography [Column: ChiralTechnologies Chiralpak AD, 10 μm; Mobile phase: 65:35 carbondioxide/(methanol containing 0.1% ammonium hydroxide)]. Thefirst-eluting enantiomer was Example 16; the later-eluting enantiomerwas Example 17.

8. Methyl 5-chloropyrazine-2-carboxylate was reacted with cesiumcarbonate and 2,2-difluoropropan-1-ol to provide methyl5-(2,2-difluoropropoxy)pyrazine-2-carboxylate; ester hydrolysis waseffected with lithium hydroxide to afford the requisite5-(2,2-difluoropropoxy)pyrazine-2-carboxylic acid.

9. Examples 18 and 19 were isolated from the corresponding racemicmaterial via supercritical fluid chromatography [Column: ChiralTechnologies Chiralpak AD, 10 μm; Mobile phase: 7:3 carbondioxide/(ethanol containing 0.1% ammonium hydroxide)]. The first-elutingenantiomer was Example 18; the later-eluting enantiomer was Example 19.

10. Reaction of methyl 5-chloropyrazine-2-carboxylate with but-2-yn-1-oland potassium tert-butoxide, followed by ester hydrolysis with lithiumhydroxide, afforded the requisite5-(but-2-yn-1-yloxy)pyrazine-2-carboxylic acid.

11. Examples 20 and 21 were isolated from the corresponding racemicmaterial via supercritical fluid chromatography [Column: ChiralTechnologies Chiralpak AD, 10 μm; Mobile phase: 7:3 carbondioxide/(ethanol containing 0.1% ammonium hydroxide)]. The first-elutingenantiomer was Example 20; the later-eluting enantiomer was Example 21.

12. Examples 22 and 23 were isolated from the corresponding racemicmaterial via supercritical fluid chromatography [Column: ChiralTechnologies Chiralpak AD, 10 μm; Mobile phase: 7:3 carbondioxide/(ethanol containing 0.1% ammonium hydroxide)]. The individualenantiomers were then purified using reversed phase HPLC (Column:Phenomenex Gemini C18, 10 μm; Mobile phase A: aqueous ammonia, pH 10;Mobile phase B: acetonitrile; Gradient: 22% to 42% B). The first-elutingenantiomer from the supercritical fluid chromatography was Example 22;the later-eluting enantiomer was Example 23.

13. Example 25 was isolated from the corresponding racemic material viasupercritical fluid chromatography [Column: Chiral TechnologiesChiralpak AD, 5 μm; Mobile phase: 7:3 carbon dioxide/(ethanol containing0.1% ammonium hydroxide)]. Example 25 was the first-eluting enantiomer;the second-eluting enantiomer was identical to Example 24.

14. Conversion of P14 to the requisite di-tert-butyl[(4aR,6R,8aR)-8a-(4-amino-1,3-thiazol-2-yl)-6-(fluoromethyl)-6-methyl-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]imidodicarbonatewas effected using the method described for synthesis of P15 from C52 inPreparation P15.

15. Examples 38 and 39 were isolated from the corresponding racemicmaterial via supercritical fluid chromatography [Column: ChiralTechnologies Chiralpak AS-H, 5 μm; Mobile phase: 85:15 carbondioxide/(methanol containing 0.2% ammonium hydroxide)]. Each enantiomerwas then individually purified via silica gel chromatography (Gradient:0% to 10% methanol in dichloromethane). The first-eluting enantiomerfrom the supercritical fluid chromatography was Example 38; thelater-eluting enantiomer was Example 39.

16. This LCMS data comes from the crude product of the final reaction;the major component exhibited m/z 468.3 [M+H]⁺.

Biological Assays

BACE1 Cell-Free Assay:

Beta-secretase (BACE) is one of the enzymes involved in the generationof the amyloid beta peptide found in the amyloid plaques of Alzheimer'sdisease patients. This assay measures the inhibition of thebeta-secretase enzyme as it cleaves a non-native peptide.

A synthetic APP substrate that can be cleaved by beta-secretase havingN-terminal biotin and made fluorescent by the covalent attachment ofOregon Green at the Cys residue is used to assay beta-secretase activityin the presence or absence of the inhibitory compounds. The substrate isBiotin-GLTNIKTEEISEISŶEVEFR-C[Oregon Green]KK-OH. The BACE1 enzyme isaffinity purified material from conditioned media of CHO-K1 cells thathave been transfected with a soluble BACE construct (BACE1deltaTM96His).Compounds are incubated in a ½ log dose response curve from a topconcentration of 100 μM with BACE1 enzyme and the biotinylatedfluorescent peptide in 384-well black plates (Thermo Scientific #4318).BACE1 is at a final concentration of 0.1 nM with a final concentrationof peptide substrate of 150 nM in a reaction volume of 30 μL assaybuffer [100 mM sodium acetate, pH 4.5 (brought to pH with acetic acid),and 0.001% Tween-20]. Plates are covered and incubated for 3 hours at37° C. The reaction is stopped with the addition of 30 μL of 1.5 μMStreptavidin (Pierce, #21125). After a 10 minute incubation at roomtemperature, plates are read on a PerkinElmer EnVision for fluorescencepolarization (Ex485 nm/Em530 nm). The activity of the beta-secretaseenzyme is detected by changes in the fluorescence polarization thatoccur when the substrate is cleaved by the enzyme. Incubation in thepresence of compound inhibitor demonstrates specific inhibition ofbeta-secretase enzymatic cleavage of the synthetic APP substrate.

TABLE 2 Biological activity and IUPAC name for Examples 1-41 BACE1Cell-free Example Assay IC₅₀ Number (μM)^(a) IUPAC Name 1 31.0N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyridine-2-carboxamide 2 0.088^(b)N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyridine-2-carboxamide 3 0.252N-{2-[cis-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3] thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide 4 >21.1N-{2-[(4a′S,8a′S)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d] [1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide 5 0.138^(b)N-{2-[(4a′R,8a′R)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d] [1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide 6 0.088N-{2-[(4a′R,8a′R)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-chloropyridine-2-carboxamide 7 0.116^(b)N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide 8 0.041N-{2-[(4aR,6S,8aR)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d] [1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide 9 0.105N-{2-[(4aR,6R,8aR)-2-amino-6-(methoxymethyl)-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy) pyridine-2-carboxamide 10 0.565N-{2-[(4aR,8aR)-2-amino-6,6-bis(fluoromethyl)-4,4a,5,6- tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide 11 6.96N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-1-(difluoromethyl)-1H-pyrazole-3-carboxamide 12 0.022N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-1-(difluoromethyl)-1H-pyrazole-3-carboxamide 13 7.95N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyrazine-2-carboxamide 14 0.167N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyrazine-2-carboxamide 15 22.2N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide 16 28.5N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(1,1-difluoroethoxy)pyridine-2-carboxamide 17 0.416N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(1,1-difluoroethoxy)pyridine-2-carboxamide 18 61.7N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(2,2-difluoropropoxy)pyrazine-2-carboxamide 19 0.421N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(2,2-difluoropropoxy)pyrazine-2-carboxamide 20 15.5N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyrazine-2-carboxamide 21 0.041N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyrazine-2-carboxamide 22 15.1N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-2-(fluoromethyl)-1,3-oxazole-4-carboxamide 23 0.017N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-2-(fluoromethyl)-1,3-oxazole-4-carboxamide 24 0.047^(b)N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)-3-methylpyridine-2-carboxamide 25 14.8N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)-3-methylpyridine-2-carboxamide 26 0.406N-{2-[(4aS,6S,8aS)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide 27 1.83N-{2-[(4aR,6R,8aR)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide 28 14.8N-{2-[(4aS,6R,8aS)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide 29 0.675N-{2-[(4a′R,8a′R)-2′-amino-4a′,5′-dihydro-4′H-spiro[oxetane-3,6′-pyrano[3,4-d][1,3] thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide 30 0.059N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-3-chloro-5-(difluoromethoxy)pyridine-2-carboxamide 31 0.911N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-2-fluoro-2-methylpropanamide 32 1.69N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-2-methoxy-2-methylpropanamide 33 0.734^(c)N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3] thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}bicyclo[1.1.1]pentane-1-carboxamide 34 0.194N-{2-[(4aR,6S,8aR)-2-amino-6-(fluoromethyl)-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy) pyridine-2-carboxamide 35 0.176N-{2-[(4aR,6R,8aR)-2-amino-6-(fluoromethyl)-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy) pyridine-2-carboxamide 36 0.060N-{2-[(4aR,6S,8aR)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)-3-methylpyridine-2-carboxamide 37 0.177N-{2-[(4aR,6S,8aR)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}bicyclo[1.1.1]pentane-2-carboxamide 38 34.5N-{2-[(4a′S,8a′S)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclopropane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide 39 0.314N-{2-[(4a′R,8a′R)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclopropane-1,6′-pyrano[3,4-d] [1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide 40 2.08N-{2-[(4aR,6S,8aR)-2-amino-6-(methoxymethyl)-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy) pyridine-2-carboxamide 41 0.714N-{2-[(4a′R,8a′R)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d] [1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-fluoropyridine-2-carboxamide ^(a)Reported IC₅₀ values are the geometricmean of 2-4 determinations, unless otherwise indicated. ^(b)The reportedIC₅₀ value is the geometric mean of ≧5 determinations. ^(c)The IC₅₀value is from a single determination.

1. A compound of Formula I

wherein R¹ is selected from the group consisting of: C₁₋₆alkyloptionally substituted with one to three fluoro or C₁₋₃alkoxy;C₅₋₉bicycloalkyl optionally substituted with one to three R⁴; and a 5-to 6-membered heteroaryl, having one to four heteroatoms independentlyselected from N, O or S, wherein at least one of the heteroatoms is Nand wherein said N is optionally substituted with R⁵; and wherein said5- to 6-membered heteroaryl is optionally substituted on carbon with oneto three R⁴; R² and R³ are each independently selected from C₁₋₆alkyl orC₃₋₇cycloalkyl; wherein the C₁₋₆alkyl is optionally substituted with oneto three fluoro or C₁₋₃alkoxy; or R² and R³ taken together with thecarbon to which they are attached form a C₃₋₆cycloalkyl ring or a 4- to6-membered heterocycloalkyl ring, each of which is optionally andindependently substituted with one to three fluoro, C₁₋₃alkyl orC₁-3alkoxy; R⁴ at each occurrence is independently selected from thegroup consisting of halogen, hydroxy, cyano, C₁₋₆alkyl, C₁₋₆alkoxy,C₃₋₆alkenyl, C₃₋₆alkenyloxy, C₃₋₆alkynyl, C₃₋₆alkynyloxy,C₁₋₆alkoxy-C₁₋₆alkyl, C₃₋₆cycloalkoxy, C₃₋₆cycloalkyl,C₃₋₆cycloalkyl-C₁₋₆alkyl, C₃₋₆cycloalkyl-C₁₋₆alkoxy, 4- to 6-memberedheterocycloalkyl and 4- to 6-membered heterocycloalkyl-C₁₋₆alkyl;wherein said C₁₋₆alkyl, C₁₋₆alkoxy, C₃₋₆alkenyl, C₃₋₆alkenyloxy,C₃₋₆alkynyl, C₃₋₆alkynyloxy, C₁₋₆alkoxy-C₁₋₆alkyl, C₃₋₆cycloalkoxy,C₃₋₆cycloalkyl, C₃₋₆cycloalkyl-C₁₋₆alkyl, C₃₋₆cycloalkyl-C₁₋₆alkoxy, 4-to 6-membered heterocycloalkyl and 4- to 6-memberedheterocycloalkyl-C₁₋₆alkyl are each optionally substituted with one tothree substituents independently selected from fluoro, chloro, hydroxy,cyano, methyl, fluoromethyl, difluoromethyl, trifluoromethyl, methoxy,fluoromethoxy, difluoromethoxy and trifluoromethoxy; and R⁵ is hydrogen,C₁₋₆alkyl, C₃₋₆alkenyl, C₃₋₆alkynyl, C₁₋₆alkoxy-C₁₋₆alkyl,C₃₋₆cycloalkyl, C₃₋₆cycloalkyl-C₁₋₆alkyl, 4- to 6-memberedheterocycloalkyl and 4- to 6-membered heterocycloalkyl-C₁₋₆alkyl;wherein said C₁₋₆alkyl, C₃₋₆alkenyl, C₃₋₆alkynyl, C₁₋₆alkoxy-C₁₋₆alkyl,C₃₋₆cycloalkyl, C₃₋₆cycloalkyl-C₁₋₆alkyl, 4- to 6-memberedheterocycloalkyl and 4- to 6-membered heterocycloalkyl-C₁₋₆alkyl areeach optionally substituted with one to three substituents independentlyselected from fluoro, chloro, hydroxy, cyano, methyl, fluoromethyl,difluoromethyl, trifluoromethyl, methoxy, fluoromethoxy, difluoromethoxyand trifluoromethoxy; or R⁴ and R⁵ taken together can be a C₃₋₅alkylene;or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.
 2. The compound of claim 1 of Formula Ia

or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.
 3. The compound of claim 1 of Formula Ib

or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.
 4. The compound of claim 1 wherein R¹ is a5-membered heteroaryl selected from the group consisting of pyrazolyland oxazolyl; each optionally substituted on carbon with one to two R⁴;and wherein said pyrazolyl is substituted on N with R⁵; R⁴ at eachoccurrence is independently selected from the group consisting ofhalogen, C₁₋₃alkyl, C₃₋₆cycloalkyl, and C₁₋₃alkoxy-C₁₋₃alkyl; whereinsaid C₁₋₃alkyl is optionally substituted with one to three fluoro; andR⁵ is C₁₋₃alkyl or C₃₋₆cycloalkyl, wherein said C₁₋₃alkyl is optionallysubstituted with one to three fluoro; or a tautomer thereof or apharmaceutically acceptable salt of said compound or tautomer.
 5. Thecompound of claim 4 wherein R¹ is selected from the group consisting of

R⁴ at each occurrence is independently selected from the groupconsisting of chloro, methyl, ethyl, isopropyl, isobutyl, fluoromethyl,difluoromethyl, trifluoromethyl, cyclopropyl, cyclobutyl andmethoxymethyl; and R⁵ is methyl, ethyl, isopropyl, difluoromethyl,cyclopropyl or cyclobutyl; or a tautomer thereof or a pharmaceuticallyacceptable salt of said compound or tautomer.
 6. The compound accordingto claim 5 wherein R¹ is selected from the group consisting of

R² and R³ are each methyl; R⁴ is fluoromethyl; and R⁵ is difluoromethyl;or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.
 7. The compound according to claim 1 wherein R¹ isa 6-membered heteroaryl selected from the group consisting of pyridinyland pyrazinyl; each optionally substituted on carbon with one to two R⁴;and R⁴ at each occurrence is independently selected from the groupconsisting of halogen, C₁₋₆alkyl, C₁₋₆alkoxy and C₃₋₆alkynyloxy; whereinsaid C₁₋₆alkyl and C₁₋₆alkoxy are optionally substituted with one tothree fluoro; or a tautomer thereof or a pharmaceutically acceptablesalt of said compound or tautomer.
 8. The compound according to claim 7wherein R¹ is selected from the group consisting of

 and R⁴ at each occurrence is independently selected from the groupconsisting of fluoro, chloro, methyl, fluoromethyl, difluoromethyl,trifluoromethyl, methoxy, fluoromethoxy, difluoromethoxy,1,1-difluoroethoxy, trifluoromethoxy, difluoropropoxy and butynyloxy; ora tautomer thereof or pharmaceutically acceptable salt of said compoundor tautomer.
 9. The compound according to claim 8 wherein R¹ is

 and R⁴ at each occurrence is independently selected from the groupconsisting of chloro, fluoro, methyl, but-2-ynyloxy, difluoromethoxy and1,1-difluoroethoxy; or a tautomer thereof or a pharmaceuticallyacceptable salt of said compound or tautomer.
 10. The compound accordingto claim 9 wherein R² and R³ are each independently selected from thegroup consisting of methyl, fluoromethyl, methoxymethyl, ethyl andcyclopropyl; or a tautomer thereof or a pharmaceutically acceptable saltof said compound or tautomer.
 11. The compound according to claim 9wherein R² and R³ taken together with the carbon to which they areattached form a cyclopropyl, cyclobutyl or oxetanyl ring; or a tautomerthereof or a pharmaceutically acceptable salt of said compound ortautomer.
 12. The compound according to claim 8 wherein R¹ is

 and R⁴ is selected from the group consisting of difluoromethoxy,2,2-difluoropropoxy and but-2-ynyloxy; or a tautomer thereof or apharmaceutically acceptable salt of said compound or tautomer.
 13. Thecompound according to claim 12 wherein R² and R³ are each methyl; or atautomer thereof or a pharmaceutically acceptable salt of said compoundor tautomer.
 14. The compound according to claim 2 wherein R¹ is aC₅₋₉bicycloalkyl; or a tautomer thereof or a pharmaceutically acceptablesalt of said compound or tautomer.
 15. The compound according to claim14 wherein R¹ is bicyclo[1.1.1]pentan-1-yl or bicyclo[1.1.1]pentan-2-yl;and R² and R³ are each independently methyl or ethyl; or a tautomerthereof or a pharmaceutically acceptable salt of said compound ortautomer.
 16. The compound according to claim 2 wherein R¹ is C₁₋₆alkyloptionally substituted with one to three fluoro or C₁₋₃alkoxy; or atautomer thereof or a pharmaceutically acceptable salt of said compoundor tautomer.
 17. The compound according to claim 16 wherein R¹ is2-fluoropropan-2-yl or 2-methoxypropan-2-yl; and R² and R³ are eachmethyl; or a tautomer thereof or a pharmaceutically acceptable salt ofsaid compound or tautomer.
 18. The compound according to claim 1selected from the group consisting of:N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyridine-2-carboxamide;N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyridine-2-carboxamide;N-{2-[cis-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;N-{2-[(4a′S,8a′S)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;N-{2-[(4a′R,8a′R)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;N-{2-[(4a′R,8a′R)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-chloropyridine-2-carboxamide;N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;N-{2-[(4aR,6S,8aR)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;N-{2-[(4aR,6R,8aR)-2-amino-6-(methoxymethyl)-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;N-{2-[(4aR,8aR)-2-amino-6,6-bis(fluoromethyl)-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-1-(difluoromethyl)-1H-pyrazole-3-carboxamide;N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-1-(difluoromethyl)-1H-pyrazole-3-carboxamide;N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyrazine-2-carboxamide;N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyrazine-2-carboxamide;N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(1,1-difluoroethoxy)pyridine-2-carboxamide;N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(1,1-difluoroethoxy)pyridine-2-carboxamide;N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(2,2-difluoropropoxy)pyrazine-2-carboxamide;N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(2,2-difluoropropoxy)pyrazine-2-carboxamide;N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyrazine-2-carboxamide;N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(but-2-yn-1-yloxy)pyrazine-2-carboxamide;N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-2-(fluoromethyl)-1,3-oxazole-4-carboxamide;N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-2-(fluoromethyl)-1,3-oxazole-4-carboxamide;N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)-3-methylpyridine-2-carboxamide;N-{2-[(4aS,8aS)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)-3-methylpyridine-2-carboxamide;N-{2-[(4aS,6S,8aS)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;N-{2-[(4aR,6R,8aR)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;N-{2-[(4aS,6R,8aS)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;N-{2-[(4a′R,8a′R)-2′-amino-4a′,5′-dihydro-4′H-spiro[oxetane-3,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-3-chloro-5-(difluoromethoxy)pyridine-2-carboxamide;N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-2-fluoro-2-methylpropanamide;N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-2-methoxy-2-methylpropanamide;N-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}bicyclo[1.1.1]pentane-1-carboxamide;N-{2-[(4aR,6S,8aR)-2-amino-6-(fluoromethyl)-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;N-{2-[(4aR,6R,8aR)-2-amino-6-(fluoromethyl)-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;N-{2-[(4aR,6S,8aR)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)-3-methylpyridine-2-carboxamide;N-{2-[(4aR,6S,8aR)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}bicyclo[1.1.1]pentane-2-carboxamide;N-{2-[(4a′S,8a′S)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclopropane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;N-{2-[(4a′R,8a′R)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclopropane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;N-{2-[(4aR,6S,8aR)-2-amino-6-(methoxymethyl)-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;andN-{2-[(4a′R,8a′R)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-fluoropyridine-2-carboxamide;or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.
 19. The compound of claim 18 which isN-{2-[(4a′R,8a′R)-2′-amino-4a′,5′-dihydro-4′H-spiro[cyclobutane-1,6′-pyrano[3,4-d][1,3]thiazin]-8a′(8′H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.
 20. The compound of claim 18 which isN-{2-[(4aR,8aR)-2-amino-6,6-dimethyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.
 21. The compound of claim 18 which isN-{2-[(4aR,6S,8aR)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.
 22. The compound of claim 18 which isN-{2-[(4aR,6R,8aR)-2-amino-6-(methoxymethyl)-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.
 23. The compound of claim 18 which isN-{2-[(4aS,6S,8aS)-2-amino-6-ethyl-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.
 24. The compound of claim 18 which isN-{2-[(4aR,6R,8aR)-2-amino-6-(fluoromethyl)-6-methyl-4,4a,5,6-tetrahydropyrano[3,4-d][1,3]thiazin-8a(8H)-yl]-1,3-thiazol-4-yl}-5-(difluoromethoxy)pyridine-2-carboxamide;or a tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer.
 25. A pharmaceutical composition comprising atherapeutically effective amount of a compound of claim 1, or a tautomerthereof or a pharmaceutically acceptable salt of said compound ortautomer, and a pharmaceutically acceptable vehicle, diluent or carrier.26.-27. (canceled)
 28. A method for treating Alzheimer's disease,treating Type 2 diabetes, of inhibiting production of amyloid-β proteinor of inhibiting beta-site amyloid precursor protein cleaving enzyme 1(BACE1) in a patient, the method comprising administering atherapeutically effective amount of a compound according to claim 1, ora tautomer thereof or a pharmaceutically acceptable salt of saidcompound or tautomer, to a patient in need of treatment of Alzheimer'sdisease, treatment of Type 2 diabetes, inhibition of production ofamyloid-β protein or inhibition of beta-site amyloid precursor proteincleaving enzyme 1 (BACE1).
 29. The method of claim 28 whereinAlzheimer's disease is treated.
 30. (canceled)
 31. The method of claim28 wherein Type 2 diabetes is treated. 32.-37. (canceled)
 38. The methodof claim 28 wherein the production of amyloid-β protein is inhibited.39. The method of claim 28 wherein beta-site amyloid precursor proteincleaving enzyme 1 (BACE1) is inhibited.